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J. J. Thomson
From Wikipedia, the free encyclopedia
This article is about the Nobel laureate and physicist. For the moral philosopher, see Judith Jarvis
Thomson.
Sir Joseph John Thomson
OM PRS
Born
18 December 1856
Cheetham Hill, Manchester, England
Died
30 August 1940 (aged 83)
Cambridge, England
Citizenship
British
Nationality
English
Fields
Physics
Institutions
Trinity College, Cambridge
Alma mater
Owens College
Trinity College, Cambridge
Academic advisors
John Strutt (Rayleigh)
Edward John Routh
Notable students
Charles Glover Barkla
Charles T. R. Wilson
Ernest Rutherford
Francis William Aston
John Townsend
J. Robert Oppenheimer
Owen Richardson
William Henry Bragg
H. Stanley Allen
John Zeleny
Daniel Frost Comstock
Max Born
T. H. Laby
Paul Langevin
Balthasar van der Pol
Geoffrey Ingram Taylor
Niels Bohr
George Paget Thomson
Known for
Plum pudding model
Discovery of electron
Discovery of isotopes
Mass spectrometer invention
First m/e measurement
Proposed first waveguide
Thomson scattering
Thomson problem
Coining term 'delta ray'
Coining term 'epsilon radiation'
Thomson (unit)
Notable awards
Smith's Prize (1880)
Royal Medal (1894)
Hughes Medal (1902)
Nobel Prize in Physics (1906)
Elliott Cresson Medal (1910)
Copley Medal (1914)
Albert Medal (1915)
Franklin Medal (1922)
Faraday Medal (1925)
Signature
Notes
Thomson is the father of Nobel laureate George Paget Thomson.
External video
The Early Life of J.J. Thomson:
Computational Chemistry and Gas
Discharge Experiments, Profiles in
Chemistry, Chemical Heritage
Foundation
Sir Joseph John Thomson OM PRS[1] (/ˈtɒmsən/; 18 December 1856 – 30 August 1940) was an
English physicist. He was elected as a fellow of the Royal Society of London[2] and appointed to the
Cavendish Professorship of Experimental Physics at the Cambridge University's Cavendish
Laboratory in 1884.[3]
In 1897, Thomson showed that cathode rays were composed of previously unknown negatively
charged particles, which he calculated must have bodies much smaller than atoms and a very large
value for their charge-to-mass ratio.[3] Thus he is credited with the discovery and identification of
the electron; and with the discovery of the first subatomic particle. Thomson is also credited with
finding the first evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his
exploration into the composition of canal rays (positive ions). His experiments to determine the
nature of positively charged particles, with Francis William Aston, were the first use of mass
spectrometry and led to the development of the mass spectrograph.[3]
Thomson was awarded the 1906 Nobel Prize in Physics for his work on the conduction of electricity
in gases.[4] Seven of his students, including his son George Paget Thomson, also became Nobel
Prize winners either in physics or in chemistry.[5] His record is comparable only to that of the German
physicist Arnold Sommerfeld.
Contents
[hide]


1Biography
2Career





o 2.1Early work
o 2.2Discovery of the electron
o 2.3Isotopes and mass spectrometry
3Experiments with cathode rays
o 3.1Experiments on the magnetic deflection of cathode rays
o 3.2Experiment to show that cathode rays were electrically charged
o 3.3Experiment to show that cathode rays could be deflected electrically
o 3.4Experiment to measure the mass to charge ratio of cathode rays
o 3.5Conclusions
o 3.6Other work
4Awards and recognition
5Notes
6References
7External links
Biography[edit]
Joseph John Thomson was born 18 December 1856 in Cheetham Hill, Manchester, Lancashire,
England. His mother, Emma Swindells, came from a local textile family. His father, Joseph James
Thomson, ran an antiquarian bookshop founded by a great-grandfather. He had a brother two years
younger than he was, Frederick Vernon Thomson.[6]
His early education was in small private schools where he demonstrated outstanding talent and
interest in science. In 1870 he was admitted to Owens College at the unusually young age of 14. His
parents planned to enroll him as an apprentice engineer to Sharp-Stewart & Co, a locomotive
manufacturer, but these plans were cut short when his father died in 1873.[6]
He moved on to Trinity College, Cambridge, in 1876. In 1880 he obtained his BA in mathematics
(Second Wrangler in the Tripos[7]and 2nd Smith's Prize).[8] He applied for and became a Fellow of
Trinity College in 1881.[9] Thomson received his MA (with Adams Prize) in 1883.[8]
Thomson was elected a Fellow of the Royal Society[1] on 12 June 1884 and served as President of
the Royal Society from 1915 to 1920.
On 22 December 1884 Thomson was chosen to become Cavendish Professor of Physics at
the University of Cambridge.[3] The appointment caused considerable surprise, given that candidates
such as Richard Glazebrook were older and more experienced in laboratory work. Thomson was
known for his work as a mathematician, where he was recognized as an exceptional talent.[10]
In 1890, Thomson married Rose Elisabeth Paget, daughter of Sir George Edward Paget, KCB, a
physician and then Regius Professor of Physic at Cambridge at the church of St. Mary the Less.
They had one son, George Paget Thomson, and one daughter, Joan Paget Thomson.
He was awarded a Nobel Prize in 1906, "in recognition of the great merits of his theoretical and
experimental investigations on the conduction of electricity by gases." He was knighted in 1908 and
appointed to the Order of Merit in 1912. In 1914 he gave the Romanes Lecture in Oxford on "The
atomic theory". In 1918 he became Master of Trinity College, Cambridge, where he remained until
his death. Joseph John Thomson died on 30 August 1940; his ashes rest in Westminster Abbey,
near the graves of Sir Isaac Newton and his former student, Ernest Rutherford.[11]
One of Thomson's greatest contributions to modern science was in his role as a highly gifted
teacher. One of his students was Ernest Rutherford, who later succeeded him as Cavendish
Professor of Physics. In addition to Thomson himself, eight of his research assistants (Francis
William Aston, Charles Glover Barkla, Niels Bohr, Max Born, William Henry Bragg, Owen Willans
Richardson, Ernest Rutherford, Charles Thomson Rees Wilson) and his son won Nobel Prizes in
physics or chemistry. His son won the Nobel Prize in 1937 for proving the wave-like properties of
electrons.
Thomson was a reserved yet devout Christian.[12]
Career[edit]
Early work[edit]
Thomson's prize-winning master's work, Treatise on the motion of vortex rings, shows his early
interest in atomic structure.[4] In it, Thomson mathematically described the motions of William
Thomson's vortex theory of atoms.[10]
Thomson published a number of papers addressing both mathematical and experimental issues of
electromagnetism. He examined the electromagnetic theory of light of James Clerk Maxwell,
introduced the concept of electromagnetic mass of a charged particle, and demonstrated that a
moving charged body would apparently increase in mass.[10]
Much of his work in mathematical modelling of chemical processes can be thought of as
early computational chemistry.[3] In further work, published in book form as Applications of dynamics
to physics and chemistry (1888), Thomson addressed the transformation of energy in mathematical
and theoretical terms, suggesting that all energy might be kinetic.[10] His next book, Notes on recent
researches in electricity and magnetism (1893), built upon Maxwell's Treatise upon electricity and
magnetism, and was sometimes referred to as "the third volume of Maxwell".[4] In it, Thomson
emphasized physical methods and experimentation and included extensive figures and diagrams of
apparatus, including a number for the passage of electricity through gases.[10] His third
book, Elements of the mathematical theory of electricity and magnetism (1895)[13] was a readable
introduction to a wide variety of subjects, and achieved considerable popularity as a textbook.[10]
A series of four lectures, given by Thomson on a visit to Princeton University in 1896, were
subsequently published as Discharge of electricity through gases (1897). Thomson also presented a
series of six lectures at Yale University in 1904.[4]
Discovery of the electron[edit]
Several scientists, such as William Prout and Norman Lockyer, had suggested that atoms were built
up from a more fundamental unit, but they envisioned this unit to be the size of the smallest atom,
hydrogen. Thomson in 1897 was the first to suggest that one of the fundamental units was more
than 1,000 times smaller than an atom, suggesting the subatomic particle now known as the
electron. Thomson discovered this through his explorations on the properties of cathode rays.
Thomson made his suggestion on 30 April 1897 following his discovery that cathode rays (at the
time known as Lenard rays) could travel much further through air than expected for an atom-sized
particle.[14] He estimated the mass of cathode rays by measuring the heat generated when the rays
hit a thermal junction and comparing this with the magnetic deflection of the rays. His experiments
suggested not only that cathode rays were over 1,000 times lighter than the hydrogen atom, but also
that their mass was the same in whichever type of atom they came from. He concluded that the rays
were composed of very light, negatively charged particles which were a universal building block of
atoms. He called the particles "corpuscles", but later scientists preferred the name electron which
had been suggested by George Johnstone Stoney in 1891, prior to Thomson's actual discovery.[15]
In April 1897, Thomson had only early indications that the cathode rays could be deflected
electrically (previous investigators such as Heinrich Hertz had thought they could not be). A month
after Thomson's announcement of the corpuscle, he found that he could reliably deflect the rays by
an electric field if he evacuated the discharge tube to a very low pressure. By comparing the
deflection of a beam of cathode rays by electric and magnetic fields he obtained more robust
measurements of the mass to charge ratio that confirmed his previous estimates.[16] This became the
classic means of measuring the charge and mass of the electron.
Thomson believed that the corpuscles emerged from the atoms of the trace gas inside his cathode
ray tubes. He thus concluded that atoms were divisible, and that the corpuscles were their building
blocks. In 1904 Thomson suggested a model of the atom, hypothesizing that it was a sphere of
positive matter within which electrostatic forces determined the positioning of the corpuscles.[3] To
explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a
uniform sea of positive charge. In this "plum pudding" model the electrons were seen as embedded
in the positive charge like plums in a plum pudding (although in Thomson's model they were not
stationary, but orbiting rapidly).[17][18]
Isotopes and mass spectrometry[edit]
In the bottom right corner of this photographic plate are markings for the two isotopes of neon: neon-20 and
neon-22.
In 1912, as part of his exploration into the composition of the streams of positively charged particles
then known as canal rays, Thomson and his research assistant F. W. Aston channelled a stream of
neon ions through a magnetic and an electric field and measured its deflection by placing a
photographic plate in its path.[6] They observed two patches of light on the photographic plate (see
image on right), which suggested two different parabolas of deflection, and concluded that neon is
composed of atoms of two different atomic masses (neon-20 and neon-22), that is to say of
two isotopes.[19] This was the first evidence for isotopes of a stable element; Frederick Soddy had
previously proposed the existence of isotopes to explain the decay of certain radioactive elements.
J.J. Thomson's separation of neon isotopes by their mass was the first example of mass
spectrometry, which was subsequently improved and developed into a general method by F. W.
Aston and by A. J. Dempster.[3]
Experiments with cathode rays[edit]
Earlier, physicists debated whether cathode rays were immaterial like light ("some process in
the aether") or were "in fact wholly material, and ... mark the paths of particles of matter charged with
negative electricity", quoting Thomson.[16] The aetherial hypothesis was vague,[16]but the particle
hypothesis was definite enough for Thomson to test.
Experiments on the magnetic deflection of cathode rays [edit]
Thomson first investigated the magnetic deflection of cathode rays. Cathode rays were produced in
the side tube on the left of the apparatus and passed through the anode into the main bell jar, where
they were deflected by a magnet. Thomson detected their path by the fluorescence on a squared
screen in the jar. He found that whatever the material of the anode and the gas in the jar, the
deflection of the rays was the same, suggesting that the rays were of the same form whatever their
origin.[20]
Experiment to show that cathode rays were electrically charged [edit]
The cathode ray tube by which J.J. Thomson demonstrated that cathode rays could be deflected by a magnetic
field, and that their negative charge was not a separate phenomenon.
While supporters of the aetherial theory accepted the possibility that negatively charged particles are
produced in Crookes tubes[citation needed], they believed that they are a mere by-product and that the
cathode rays themselves are immaterial[citation needed]. Thomson set out to investigate whether or not he
could actually separate the charge from the rays.
Thomson constructed a Crookes tube with an electrometer set to one side, out of the direct path of
the cathode rays. Thomson could trace the path of the ray by observing the phosphorescent patch it
created where it hit the surface of the tube. Thomson observed that the electrometer registered a
charge only when he deflected the cathode ray to it with a magnet. He concluded that the negative
charge and the rays were one and the same.[14]
Experiment to show that cathode rays could be deflected electrically[edit]
Thomson's illustration of the Crookes tube by which he observed the deflection of cathode rays by an electric
field (and later measured their mass to charge ratio). Cathode rays were emitted from the cathode C, passed
through slits A (the anode) and B (grounded), then through the electric field generated between plates D and E,
finally impacting the surface at the far end.
The cathode ray (blue line) was deflected by the electric field (yellow).
In May–June 1897, Thomson investigated whether or not the rays could be deflected by an electric
field.[6] Previous experimenters had failed to observe this, but Thomson believed their experiments
were flawed because their tubes contained too much gas.
Thomson constructed a Crookes tube with a better vacuum. At the start of the tube was the cathode
from which the rays projected. The rays were sharpened to a beam by two metal slits – the first of
these slits doubled as the anode, the second was connected to the earth. The beam then passed
between two parallel aluminium plates, which produced an electric field between them when they
were connected to a battery. The end of the tube was a large sphere where the beam would impact
on the glass, created a glowing patch. Thomson pasted a scale to the surface of this sphere to
measure the deflection of the beam. Note that any electron beam would collide with some residual
gas atoms within the Crookes tube, thereby ionizing them and producing electrons and ions in the
tube (space charge); in previous experiments this space charge electrically screened the externally
applied electric field. However, in Thomson's Crookes tube the density of residual atoms was so low
that the space charge from the electrons and ions was insufficient to electrically screen the
externally applied electric field, which permitted Thomson to successfully observe electrical
deflection.
When the upper plate was connected to the negative pole of the battery and the lower plate to the
positive pole, the glowing patch moved downwards, and when the polarity was reversed, the patch
moved upwards.
Experiment to measure the mass to charge ratio of cathode rays[edit]
In his classic experiment, Thomson measured the mass-to-charge ratio of the cathode rays by
measuring how much they were deflected by a magnetic field and comparing this with the electric
deflection. He used the same apparatus as in his previous experiment, but placed the discharge
tube between the poles of a large electromagnet. He found that the mass to charge ratio was over a
thousand times lower than that of a hydrogen ion (H+), suggesting either that the particles were very
light and/or very highly charged.[16] Significantly, the rays from every cathode yielded the same massto-charge ratio. This is in contrast to anode rays (now known to arise from positive ions emitted by
the anode), where the mass-to-charge ratio varies from anode-to-anode. Thomson himself remained
critical of what his work established, in his Nobel Prize acceptance speech referring to "corpuscles"
rather than "electrons".
Thomson's calculations can be summarised as follows (notice that we reproduce here Thomson's
original notations, using F instead of E for the electric field and H instead of B for the magnetic field):
The electric deflection is given by Θ = Fel/mv2 where Θ is the angular electric deflection, F is applied
electric intensity, e is the charge of the cathode ray particles, l is the length of the electric plates, m is
the mass of the cathode ray particles and v is the velocity of the cathode ray particles.
The magnetic deflection is given by φ = Hel/mv where φ is the angular magnetic deflection and H is
the applied magnetic field intensity.
The magnetic field was varied until the magnetic and electric deflections were the same, when Θ = φ
and Fel/mv2= Hel/mv. This can be simplified to give m/e = H2l/FΘ. The electric deflection was
measured separately to give Θ and H, F and l were known, so m/e could be calculated.
Conclusions[edit]
As the cathode rays carry a charge of negative electricity, are deflected by an electrostatic force as if
they were negatively electrified, and are acted on by a magnetic force in just the way in which this
force would act on a negatively electrified body moving along the path of these rays, I can see no
escape from the conclusion that they are charges of negative electricity carried by particles of
matter.
— J. J. Thomson[16]
As to the source of these particles, Thomson believed they emerged from the molecules of gas in
the vicinity of the cathode.
If, in the very intense electric field in the neighbourhood of the cathode, the molecules of the gas are
dissociated and are split up, not into the ordinary chemical atoms, but into these primordial atoms,
which we shall for brevity call corpuscles; and if these corpuscles are charged with electricity and
projected from the cathode by the electric field, they would behave exactly like the cathode rays.
— J. J. Thomson[21]
Thomson imagined the atom as being made up of these corpuscles orbiting in a sea of positive
charge; this was his plum pudding model. This model was later proved incorrect when his
student Ernest Rutherford showed that the positive charge is concentrated in the nucleus of the
atom.
Other work[edit]
In 1905, Thomson discovered the natural radioactivity of potassium.[22]
In 1906, Thomson demonstrated that hydrogen had only a single electron per atom. Previous
theories allowed various numbers of electrons.[23][24]
Awards and recognition[edit]
Plaque commemorating J. J. Thomson's discovery of the electron outside the old Cavendish Laboratory in
Cambridge







Adams Prize (1882)
Royal Medal (1894)
Hughes Medal (1902)
Nobel Prize for Physics (1906)
Elliott Cresson Medal (1910)
Copley Medal (1914)
Franklin Medal (1922)
In 1991, the thomson (symbol: Th) was proposed as a unit to measure mass-to-charge ratio in mass
spectrometry in his honour.[25]
J J Thomson Avenue, on the University of Cambridge campus, is named after Thomson.[26]
In November 1927, J.J. Thomson opened the Thomson building, named in his honour, in the Leys
School, Cambridge.[27]
Notes[edit]
1.
^ Jump up to:a b
Ernest Rutherford
From Wikipedia, the free encyclopedia
"Lord Rutherford" redirects here. It is not to be confused with Lord Rutherfurd or Andrew Rutherford,
1st Earl of Teviot.
The Right Honourable
The Lord Rutherford of Nelson
OM FRS
President of the Royal Society
In office
1925–1930
Preceded by
Sir Charles Scott Sherrington
Succeeded by
Sir Frederick Gowland Hopkins
Personal details
Born
30 August 1871
Brightwater, Tasman District, New Zealand
Died
19 October 1937 (aged 66)
Cambridge, England, UK
Citizenship
British subject
Nationality
New Zealander
New Zealand, United Kingdom
Residence
Signature
Scientific career
Fields
Physics and Chemistry
Institutions
McGill University
University of Manchester
University of Cambridge
University of Canterbury
Alma mater
University of Cambridge
Academic advisors
Alexander Bickerton
J. J. Thomson
Doctoral students

Nazir Ahmed

Norman Alexander

Edward Victor Appleton

Robert William Boyle

James Chadwick

Rafi Muhammad Chaudhry

Norman Feather
Daulat Singh Kothari
Other notable

Alexander MacAulay

Cecil Powell

Henry DeWolf Smyth

Ernest Walton

Evan James Williams

C. E. Wynn-Williams

Yulii Borisovich Khariton

Edward Andrade
students
Known for

Edward Victor Appleton

Patrick Blackett

Niels Bohr

Bertram Boltwood

Harriet Brooks

Teddy Bullard

John Cockcroft

Charles Galton Darwin

Charles Drummond Ellis

Kazimierz Fajans

Hans Geiger

Otto Hahn

Douglas Hartree

Pyotr Kapitsa

George Laurence

Iven Mackay

Ernest Marsden

Mark Oliphant

Thomas Royds

Frederick Soddy

Discovery of alpha and beta radioactivity

Discovery of atomic nucleus(Rutherford
model)

Rutherford scattering
Rutherford backscattering spectroscopy

Discovery of proton

Rutherford (unit)

Coining the term 'artificial disintegration'
Henry Moseley
Influenced
Hans Geiger
Albert Beaumont Wood
Notable awards 
Rumford Medal (1904)

Nobel Prize in Chemistry (1908)

Barnard Medal (1910)

Elliott Cresson Medal (1910)

Matteucci Medal (1913)

Copley Medal (1922)

Franklin Medal (1924)

Albert Medal (1928)

Faraday Medal (1930)
Wilhelm Exner Medal (1936)
Ernest Rutherford, 1st Baron Rutherford of Nelson, OM, FRS[1] (30 August 1871 – 19 October
1937) was a New Zealand physicist who came to be known as the father of nuclear
physics.[2] Encyclopædia Britannica considers him to be the greatest experimentalist since Michael
Faraday (1791–1867).[2]
In early work, Rutherford discovered the concept of radioactive half-life, proved that radioactivity
involved the nuclear transmutation of one chemical element to another, and also differentiated and
named alpha and beta radiation.[3] This work was done at McGill University in Canada. It is the basis
for the Nobel Prize in Chemistry he was awarded in 1908 "for his investigations into the
disintegration of the elements, and the chemistry of radioactive substances",[4] for which he is the first
Canadian and Oceanian Nobel laureate, and remains the only laureate born in the South Island.
Rutherford moved in 1907 to the Victoria University of Manchester (today University of Manchester)
in the UK, where he and Thomas Royds proved that alpha radiation is helium nuclei.[5][6] Rutherford
performed his most famous work after he became a Nobel laureate.[4] In 1911, although he could not
prove that it was positive or negative,[7] he theorized that atoms have their charge concentrated in a
very small nucleus,[8] and thereby pioneered the Rutherford model of the atom, through his discovery
and interpretation of Rutherford scattering by the gold foil experiment of Hans Geiger and Ernest
Marsden. He conducted research that led to the first "splitting" of the atom in 1917 in a nuclear
reaction between nitrogen and alpha particles, in which he also discovered (and named) the proton.[9]
Rutherford became Director of the Cavendish Laboratory at the University of Cambridge in 1919.
Under his leadership the neutron was discovered by James Chadwick in 1932 and in the same year
the first experiment to split the nucleus in a fully controlled manner was performed by students
working under his direction, John Cockcroft and Ernest Walton. After his death in 1937, he was
honoured by being interred with the greatest scientists of the United Kingdom, near Sir Isaac
Newton's tomb in Westminster Abbey. The chemical element rutherfordium (element 104) was
named after him in 1997.
Contents
[hide]





1Biography
o 1.1Early life and education
o 1.2Later years and honours
2Scientific research
o 2.1Gold foil experiment
3Legacy
o 3.1Nuclear physics
o 3.2Items named in honour of Rutherford's life and work
4Incidences of cancer at Rutherford's former laboratory
5Publications





o 5.1Articles
6Styles of address and arms
o 6.1Styles of address
o 6.2Arms
7See also
8References
9Further reading
10External links
Biography
Early life and education
Rutherford aged 21
Ernest Rutherford was the son of James Rutherford, a farmer, and his wife Martha Thompson,
originally from Hornchurch, Essex, England.[10] James had emigrated to New Zealand from Perth,
Scotland, "to raise a little flax and a lot of children". Ernest was born at Brightwater, near Nelson,
New Zealand. His first name was mistakenly spelled 'Earnest' when his birth was
registered.[11] Rutherford's mother Martha Thompson was a schoolteacher.[12]
He studied at Havelock School and then Nelson College and won a scholarship to study
at Canterbury College, University of New Zealand, where he participated in the debating society and
played rugby.[13] After gaining his BA, MA and BSc, and doing two years of research during which he
invented a new form of radio receiver, in 1895 Rutherford was awarded an 1851 Research
Fellowship from the Royal Commission for the Exhibition of 1851,[14] to travel to England for
postgraduate study at the Cavendish Laboratory, University of Cambridge.[15] He was among the first
of the 'aliens' (those without a Cambridge degree) allowed to do research at the university, under the
inspiring leadership of J. J. Thomson, and the newcomers aroused jealousies from the more
conservative members of the Cavendish fraternity. With Thomson's encouragement, he managed to
detect radio waves at half a mile and briefly held the world record for the distance over which
electromagnetic waves could be detected, though when he presented his results at the British
Association meeting in 1896, he discovered he had been outdone by another lecturer, by the name
of Marconi.
In 1898 Thomson recommended Rutherford for a position at McGill University in Montreal, Canada.
He was to replace Hugh Longbourne Callendar who held the chair of Macdonald Professor of
physics and was coming to Cambridge.[16] Rutherford was accepted, which meant that in 1900 he
could marry Mary Georgina Newton (1876–1954)[17][18] to whom he had become engaged before
leaving New Zealand; they had one daughter, Eileen Mary (1901–1930), who married Ralph Fowler.
In 1900 he gained a DSc from the University of New Zealand. In 1907 Rutherford returned to Britain
to take the chair of physics at the Victoria University of Manchester.
Later years and honours
He was knighted in 1914.[19] During World War I, he worked on a top secret project to solve the
practical problems of submarine detection by sonar.[20] In 1916 he was awarded the Hector Memorial
Medal. In 1919 he returned to the Cavendish succeeding J. J. Thomson as the Cavendish professor
and Director. Under him, Nobel Prizes were awarded to James Chadwick for discovering the neutron
(in 1932), John Cockcroft and Ernest Walton for an experiment which was to be known as splitting
the atom using a particle accelerator, and Edward Appleton for demonstrating the existence of
the ionosphere. In 1925, Rutherford pushed calls to the Government of New Zealand to support
education and research, which led to the formation of the Department of Scientific and Industrial
Research (DSIR) in the following year.[21] Between 1925 and 1930 he served as President of the
Royal Society, and later as president of the Academic Assistance Council which helped almost
1,000 university refugees from Germany.[2] He was appointed to the Order of Merit in the 1925 New
Year Honours[22] and raised to the peerage as Baron Rutherford of Nelson, of Cambridge in the
County of Cambridge in 1931,[23] a title that became extinct upon his unexpected death in 1937. In
1933, Rutherford was one of the two inaugural recipients of the T. K. Sidey Medal, set up by
the Royal Society of New Zealand as an award for outstanding scientific research.[24][25]
Lord Rutherford's grave in Westminster Abbey
For some time before his death, Rutherford had a small hernia, which he had neglected to have
fixed, and it became strangulated, causing him to be violently ill. Despite an emergency operation in
London, he died four days afterwards of what physicians termed "intestinal paralysis", at
Cambridge.[26] After cremation at Golders Green Crematorium,[26] he was given the high honour of
burial in Westminster Abbey, near Isaac Newton and other illustrious British scientists.[27]
Scientific research
Ernest Rutherford at the McGill University in 1905
At Cambridge, Rutherford started to work with J. J. Thomson on the conductive effects of X-rays on
gases, work which led to the discovery of the electron which Thomson presented to the world in
1897. Hearing of Becquerel's experience with uranium, Rutherford started to explore its radioactivity,
discovering two types that differed from X-rays in their penetrating power. Continuing his research in
Canada, he coined the terms alpha ray and beta ray in 1899 to describe the two distinct types
of radiation. He then discovered that thorium gave off a gas which produced an emanation which
was itself radioactive and would coat other substances. He found that a sample of this radioactive
material of any size invariably took the same amount of time for half the sample to decay – its "halflife" (11½ minutes in this case).
From 1900 to 1903, he was joined at McGill by the young chemist Frederick Soddy (Nobel Prize in
Chemistry, 1921) for whom he set the problem of identifying the thorium emanations. Once he had
eliminated all the normal chemical reactions, Soddy suggested that it must be one of the inert gases,
which they named thoron (later found to be an isotope of radon). They also found another type of
thorium they called Thorium X, and kept on finding traces of helium. They also worked with samples
of "Uranium X" from William Crookes and radium from Marie Curie.
In 1902, they produced a "Theory of Atomic Disintegration" to account for all their experiments. Up
till then atoms were assumed to be the indestructable basis of all matter and although Curie had
suggested that radioactivity was an atomic phenomenon, the idea of the atoms of radioactive
substances breaking up was a radically new idea. Rutherford and Soddy demonstrated that
radioactivity involved the spontaneous disintegration of atoms into other types of atoms (one
element spontaneously being changed to another).
In 1903, Rutherford considered a type of radiation discovered (but not named) by French
chemist Paul Villard in 1900, as an emission from radium, and realised that this observation must
represent something different from his own alpha and beta rays, due to its very much greater
penetrating power. Rutherford therefore gave this third type of radiation the name of gamma ray. All
three of Rutherford's terms are in standard use today – other types of radioactive decay have since
been discovered, but Rutherford's three types are among the most common.
In Manchester, he continued to work with alpha radiation. In conjunction with Hans Geiger, he
developed zinc sulfide scintillation screens and ionisation chambers to count alphas. By dividing the
total charge they produced by the number counted, Rutherford decided that the charge on the alpha
was two. In late 1907, Ernest Rutherford and Thomas Royds allowed alphas to penetrate a very thin
window into an evacuated tube. As they sparked the tube into discharge, the spectrum obtained
from it changed, as the alphas accumulated in the tube. Eventually, the clear spectrum of helium gas
appeared, proving that alphas were at least ionised helium atoms, and probably helium nuclei.
Gold foil experiment
Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed.
Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated
charge. Note that the image is not to scale; in reality the nucleus is vastly smaller than the electron shell.
Rutherford performed his most famous work after receiving the Nobel prize in 1908. Along with Hans
Geiger and Ernest Marsden in 1909, he carried out the Geiger–Marsden experiment, which
demonstrated the nuclear nature of atoms by deflecting alpha particles passing through a thin gold
foil. Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles
with very high deflection angles, of a type not expected from any theory of matter at that time. Such
deflections, though rare, were found, and proved to be a smooth but high-order function of the
deflection angle. It was Rutherford's interpretation of this data that led him to formulate
the Rutherford model of the atom in 1911 – that a very small charged [7] nucleus, containing much of
the atom's mass, was orbited by low-mass electrons.
Before leaving Manchester in 1919 to take over the Cavendish laboratory in Cambridge, Rutherford
became, in 1919, the first person to deliberately transmute one element into another.[4] In this
experiment, he had discovered peculiar radiations when alphas were projected into air, and
narrowed the effect down to the nitrogen, not the oxygen in the air. Using pure nitrogen, Rutherford
used alpha radiation to convert nitrogen into oxygen through the nuclear reaction 14N + α → 17O +
proton. The proton was not then known. In the products of this reaction Rutherford simply identified
hydrogen nuclei, by their similarity to the particle radiation from earlier experiments in which he had
bombarded hydrogen gas with alpha particles to knock hydrogen nuclei out of hydrogen atoms. This
result showed Rutherford that hydrogen nuclei were a part of nitrogen nuclei (and by inference,
probably other nuclei as well). Such a construction had been suspected for many years on the basis
of atomic weights which were whole numbers of that of hydrogen; see Prout's hypothesis. Hydrogen
was known to be the lightest element, and its nuclei presumably the lightest nuclei. Now, because of
all these considerations, Rutherford decided that a hydrogen nucleus was possibly a fundamental
building block of all nuclei, and also possibly a new fundamental particle as well, since nothing was
known from the nucleus that was lighter. Thus, Rutherford postulated the hydrogen nucleus to be a
new particle in 1920, which he dubbed the proton.
In 1921, while working with Niels Bohr (who postulated that electrons moved in specific orbits),
Rutherford theorized about the existence of neutrons, (which he had christened in his 1920 Bakerian
Lecture), which could somehow compensate for the repelling effect of the positive charges
of protons by causing an attractive nuclear force and thus keep the nuclei from flying apart from the
repulsion between protons. The only alternative to neutrons was the existence of "nuclear electrons"
which would counteract some of the proton charges in the nucleus, since by then it was known that
nuclei had about twice the mass that could be accounted for if they were simply assembled from
hydrogen nuclei (protons). But how these nuclear electrons could be trapped in the nucleus, was a
mystery.
Rutherford's theory of neutrons was proved in 1932 by his associate James Chadwick, who
recognized neutrons immediately when they were produced by other scientists and later himself, in
bombarding beryllium with alpha particles. In 1935, Chadwick was awarded the Nobel Prize in
Physics for this discovery.
Legacy
A plaque commemorating Rutherford's presence at the University of Manchester
Nuclear physics
Rutherford's research, and work done under him as laboratory director, established the nuclear
structure of the atom and the essential nature of radioactive decay as a nuclear process.
Rutherford's team, using natural alpha particles, demonstrated induced nuclear transmutation, and
later, using protons from an accelerator, demonstrated artificially-induced nuclear reactions and
transmutation. He is known as the father of nuclear physics. Rutherford died too early to see Leó
Szilárd's idea of controlled nuclear chain reactions come into being. However, a speech of
Rutherford's about his artificially-induced transmutation in lithium, printed in 12 September 1933
London paper The Times, was reported by Szilárd to have been his inspiration for thinking of the
possibility of a controlled energy-producing nuclear chain reaction. Szilard had this idea while
walking in London, on the same day.
Rutherford's speech touched on the 1932 work of his students John Cockcroft and Ernest Walton in
"splitting" lithium into alpha particles by bombardment with protons from a particle accelerator they
had constructed. Rutherford realized that the energy released from the split lithium atoms was
enormous, but he also realized that the energy needed for the accelerator, and its essential
inefficiency in splitting atoms in this fashion, made the project an impossibility as a practical source
of energy (accelerator-induced fission of light elements remains too inefficient to be used in this way,
even today). Rutherford's speech in part, read:
We might in these processes obtain very much more energy than the proton supplied, but on the
average we could not expect to obtain energy in this way. It was a very poor and inefficient way of
producing energy, and anyone who looked for a source of power in the transformation of the atoms
was talking moonshine. But the subject was scientifically interesting because it gave insight into the
atoms.[28]
Items named in honour of Rutherford's life and work
A statue of a young Ernest Rutherford at his memorial in Brightwater, New Zealand.
Scientific discoveries
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The element rutherfordium, Rf, Z=104. (1997)[29]
The rutherford (Rd), an obsolete unit of radioactivity equivalent to one megabecquerel.
Institutions
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Rutherford Appleton Laboratory, a scientific research laboratory near Didcot, Oxfordshire.
Rutherford College, Auckland, a school in Auckland, New Zealand
Rutherford College, Kent, a college at the University of Kent in Canterbury, England
Rutherford Institute for Innovation at the University of Cambridge
Rutherford Intermediate School, Wanganui, New Zealand
Rutherford Hall, a hall of residence at Loughborough University
Awards
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Rutherford Medal, the highest science medal awarded by the Royal Society of New Zealand
Rutherford Award at Thomas Carr College for excellence in Victorian Certificate of
Education chemistry, Australia.
 Rutherford Memorial Medal is an award for research in the fields of physics and chemistry by
the Royal Society of Canada.
 Rutherford Medal and Prize is awarded once every two years by the Institute of Physics for
"distinguished research in nuclear physics or nuclear technology".
 Rutherford Memorial Lecture is an international lecture tour under the auspices of the Royal
Society created under the Rutherford Memorial Scheme in 1952.
Buildings
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Rutherford House, a boarding house at Nelson College[30]
Rutherford Hotel, Nelson's largest hotel, which incorporates the Rutherford Cafe and Bar
The physics and chemistry building at the University of Canterbury, New Zealand
Rochester and Rutherford Hall at the University of Canterbury, New Zealand
Rutherford House, the primary building of Victoria University of Wellington's Pipitea Campus,
originally the headquarters of the New Zealand Electricity Department, in Wellington, New
Zealand.
 Rutherford building at Bedford Modern School.
 A building of the modern Cavendish Laboratory at the University of Cambridge
 The Ernest Rutherford Physics Building at McGill University, Montreal[31]
 The Coupland Building at the University of Manchester, where Rutherford worked, was renamed
"The Rutherford Building" in 2006.
 The Rutherford lecture theatre in the Schuster Laboratory at the University of Manchester
Major streets
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Lord Rutherford Road (the location of his birthplace in Brightwater, New Zealand)
Rutherford Street, a major thoroughfare in central Nelson, New Zealand
Rutherford Close, a residential street in Abingdon, Oxfordshire
Rutherford Road in the biotechnology district of Carlsbad, California
Rutherford Road, commercial/residential street in Vaughan, Ontario, Canada
Other
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Rutherford Park, a sports ground in Nelson, New Zealand
The Rutherford Memorial at the site of his birth in Brightwater, New Zealand
His image is on the obverse of the New Zealand one hundred-dollar note (since 1992).
The Rutherford Foundation, a charitable trust set up by the Royal Society of New Zealand to
support research in science and technology.[32]
Rutherford House, at Macleans College, Auckland, New Zealand
Rutherford House, at Hillcrest High School, Hamilton, New Zealand
Rutherford House, at Rotorua Intermediate School, Rotorua, New Zealand
Rutherford House, at Rangiora High School
The crater Rutherford on the Moon, and the crater Rutherford on the planet Mars
Ernest Rutherford was the subject of a play by Stuart Hoar.
On the side of the Mond Laboratory on the site of the original Cavendish Laboratory in
Cambridge, there is an engraving in Rutherford's memory in the form of a crocodile, this being
the nickname given to him by its commissioner, his colleague Peter Kapitza.
Rutherford rocket engine, an engine developed in New Zealand by Rocket Lab and the first to
use the electric pump feed cycle.
His image is depicted in the stained glass window of the Presbyterian chapel at Lindisfarne
College in Hastings, New Zealand. The window, unveiled in 2007, is dedicated to the college's
concept of men with supreme content of character, and depicts Rutherford along with Charles
Upham, Edmund Hillary, and John Rangihau as iconic examples.
Incidences of cancer at Rutherford's former laboratory
The Coupland Building at Manchester University, at which Rutherford conducted many of his
experiments, has been the subject of a cancer cluster investigation. There has been a statistically
high incidence of pancreatic cancer, brain cancer, and motor neuron disease occurring in and
around Rutherford's former laboratories and, since 1984, a total of six workers have been stricken
with these ailments. In 2009, an independent commission concluded that the very slightly elevated
levels of various radiation related to Rutherford's experiments decades earlier are not the likely
cause of such cancers and ruled the illnesses a coincidence.[33]
John Dalton
From Wikipedia, the free encyclopedia
For other people named John Dalton, see John Dalton (disambiguation).
John Dalton
Dalton by Charles Turner
after James Lonsdale
(1834, mezzotint)
Born
6 September 1766
Eaglesfield, Cumberland, England
Died
27 July 1844 (aged 77)
Manchester, England
Stroke
Nationality
British
Notable students
James Prescott Joule
Known for
Atomic theory, Law of Multiple
Proportions, Dalton's Law of Partial
Pressures, Daltonism
Influences
John Gough
Notable awards
Royal Medal (1826)
Author abbrev.
Jn.Dalton
(botany)
Signature
John Dalton FRS (6 September 1766 – 27 July 1844) was an English chemist, physicist,
and meteorologist. He is best known for his pioneering work in the development of modern atomic
theory; and his research into colour blindness, sometimes referred to as Daltonism, in his honour.
Contents
[hide]
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1Early life
2Early careers
3Scientific contributions
o 3.1Meteorology
o 3.2Colour blindness
o 3.3Measuring mountains in the Lake District
o 3.4Gas laws
o 3.5Atomic theory
o 3.6Atomic weights
o 3.7Other investigations
o 3.8Experimental approach
4Other publications
5Public life
6Personal life
7Disability and death
8Legacy
9See also
10References
11Sources
12External links
Early life
John Dalton was born into a Quaker family in Eaglesfield, near Cockermouth, in the county
of Cumberland, England.[1] His father was a weaver. He received his early education from his father
and from Quaker John Fletcher, who ran a private school in the nearby village of Pardshaw Hall.
With his family too poor to support him for long, he began to earn his living at the age of ten in the
service of a wealthy local Quaker, Elihu Robinson.[2] It is said he began teaching at a local school at
age 12, and was proficient in Latin at age 14.
Early careers
He joined his older brother Jonathan at age 15 in running a Quaker school in Kendal, about forty five
miles from his home. Around age 23 Dalton may have considered studying law or medicine, but his
relatives did not encourage him, perhaps because being a Dissenter, he was barred from attending
English universities. He acquired much scientific knowledge from informal instruction by John
Gough, a blind philosopher who was gifted in the sciences and arts. At age 27 he was appointed
teacher of mathematics and natural philosophy at the "New College" in Manchester, a dissenting
academy. He remained there until age 34, when the college's worsening financial situation led him to
resign his post and begin a new career as a private tutor for mathematics and natural philosophy.
Scientific contributions
Meteorology
Dalton's early life was highly influenced by a prominent Eaglesfield Quaker named Elihu
Robinson,[3] a competent meteorologist and instrument maker, who got him interested in problems of
mathematics and meteorology. During his years in Kendal, Dalton contributed solutions of problems
and questions on various subjects to The Ladies' Diary and the Gentleman's Diary. In 1787 at age
21 he began to keep a meteorological diary in which, during the succeeding 57 years, he entered
more than 200,000 observations.[4] He also rediscovered George Hadley's theory of atmospheric
circulation (now known as the Hadley cell) around this time.[5] Dalton's first publication
was Meteorological Observations and Essays at age 27 in 1793, which contained the seeds of
several of his later discoveries. However, in spite of the originality of his treatment, little attention
was paid to them by other scholars. A second work by Dalton, Elements of English Grammar, was
published at age 35 in 1801.
Colour blindness
In 1794 at age 28, shortly after his arrival in Manchester, Dalton was elected a member of
the Manchester Literary and Philosophical Society, the "Lit & Phil", and a few weeks later he
communicated his first paper on "Extraordinary facts relating to the vision of colours", in which he
postulated that shortage in colour perception was caused by discoloration of the liquid medium of the
eyeball. In fact, a shortage of colour perception in some people had not even been formally
described or officially noticed until Dalton wrote about his own.[citation needed] Since both he and his
brother were colour blind, he recognized that this condition must be hereditary.[6]
Although Dalton's theory lost credence in his own lifetime, the thorough and methodical nature of his
research into his own visual problem was so broadly recognized that Daltonism became a common
term for colour blindness.[7] Examination of his preserved eyeball in 1995 demonstrated that Dalton
actually had a less common kind of colour blindness, deuteroanopia, in which medium wavelength
sensitive cones are missing (rather than functioning with a mutated form of their pigment, as in the
most common type of colour blindness, deuteroanomaly).[6] Besides the blue and purple of the
optical spectrum he was able to recognize only one colour, yellow, or, as he says in his paper,
that part of the image which others call red appears to me little more than a shade or defect of light.
After that the orange, yellow and green seem one colour which descends pretty uniformly from an
intense to a rare yellow, making what I should call different shades of yellow
Measuring mountains in the Lake District
Dalton regularly holidayed in the Lake District where his study of meteorology involved a lot of
mountain climbing: until the advent of aeroplanes and weather balloons, the only way to make
measurements of temperature and humidity at altitude was to climb a mountain. The altitude
achieved was estimated using a barometer. This meant that, until the Ordnance Survey started
publishing their maps for the Lake District in the 1860s, Dalton was one of the few sources of such
information.[8] Dalton was often accompanied by Jonathan Otley, who was one of the few other
authorities on the heights of the Lake District mountains. He became both an assistant and a friend.[9]
Gas laws
External video
Profiles in Chemistry:How John
Dalton's meteorological studies led to the
discovery of atoms on YouTube, Chemical
Heritage Foundation
In 1800, at age 34 Dalton became a secretary of the Manchester Literary and Philosophical Society,
and in the following year he orally presented an important series of papers, entitled "Experimental
Essays" on the constitution of mixed gases; on the pressure of steam and other vapours at different
temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases.
These four essays were published in the Memoirs of the Lit & Phil in 1802.
The second of these essays opens with the striking remark,
There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever
kind, into liquids; and we ought not to despair of effecting it in low temperatures and by strong
pressures exerted upon the unmixed gases further.
After describing experiments to ascertain the pressure of steam at various points between 0 and
100 °C (32 and 212 °F), Dalton concluded from observations on the vapour pressure of six different
liquids, that the variation of vapour pressure for all liquids is equivalent, for the same variation of
temperature, reckoning from vapour of any given pressure.
In the fourth essay he remarks,[10]
I see no sufficient reason why we may not conclude that all elastic fluids under the same pressure
expand equally by heat and that for any given expansion of mercury, the corresponding expansion of
air is proportionally something less, the higher the temperature. It seems, therefore, that general
laws respecting the absolute quantity and the nature of heat are more likely to be derived from
elastic fluids than from other substances.
He thus enunciated Gay-Lussac's law or J.A.C. Charles's law, published in 1802 at age 36
by Joseph Louis Gay-Lussac. In the two or three years following the reading of these essays, Dalton
published several papers on similar topics, that on the absorption of gases by water and other liquids
(1803), containing his law of partial pressures now known as Dalton's law.
Atomic theory
The most important of all Dalton's investigations are those concerned with the atomic theory in
chemistry. While his name is inseparably associated with this theory, the origin of Dalton's atomic
theory is not fully understood.[11] It has been proposed that this theory was suggested to him either by
researches on ethylene (olefiant gas) and methane(carburetted hydrogen) or by analysis of nitrous
oxide (protoxide of azote) and nitrogen dioxide (deutoxide of azote), both views resting on the
authority of Thomas Thomson.[12]However, a study of Dalton's own laboratory notebooks, discovered
in the rooms of the Lit & Phil,[13] concluded that so far from Dalton being led by his search for an
explanation of the law of multiple proportions to the idea that chemical combination consists in the
interaction of atoms of definite and characteristic weight, the idea of atoms arose in his mind as a
purely physical concept, forced upon him by study of the physical properties of the atmosphere and
other gases. The first published indications of this idea are to be found at the end of his paper on the
absorption of gases already mentioned, which was read on 21 October 1803, though not published
until 1805. Here he says:
Why does not water admit its bulk of every kind of gas alike? This question I have duly considered,
and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance
depends on the weight and number of the ultimate particles of the several gases.
The main points of Dalton's atomic theory were:
1. Elements are made of extremely small particles called atoms.
2. Atoms of a given element are identical in size, mass, and other properties; atoms of different
elements differ in size, mass, and other properties.
3. Atoms cannot be subdivided, created, or destroyed.
4. Atoms of different elements combine in simple whole-number ratios to form chemical
compounds.
5. In chemical reactions, atoms are combined, separated, or rearranged.
Dalton proposed an additional "rule of greatest simplicity" that created controversy, since it could not
be independently confirmed.
When atoms combine in only one ratio, "..it must be presumed to be a binary one, unless
some cause appear to the contrary".
For elements that combined in multiple ratios, their combinations were assumed to be the
simplest ones possible. Two combinations resulted in a binary and a ternary compound.[14] This
was merely an assumption, derived from faith in the simplicity of nature. No evidence was then
available to scientists to deduce how many atoms of each element combine to form compound
molecules. But this or some other such rule was absolutely necessary to any incipient theory,
since one needed an assumed molecular formula in order to calculate relative atomic weights. In
any case, Dalton's "rule of greatest simplicity" caused him to assume that the formula for water
was OH and ammonia was NH, quite different from our modern understanding (H2O, NH3).
Despite the uncertainty at the heart of Dalton's atomic theory, the principles of the theory
survived. To be sure, the conviction that atoms cannot be subdivided, created, or destroyed into
smaller particles when they are combined, separated, or rearranged in chemical reactions is
inconsistent with the existence of nuclear fusion and nuclear fission, but such processes are
nuclear reactions and not chemical reactions. In addition, the idea that all atoms of a given
element are identical in their physical and chemical properties is not precisely true, as we now
know that different isotopes of an element have slightly varying weights. However, Dalton had
created a theory of immense power and importance. Indeed, Dalton's innovation was fully as
important for the future of the science as Antoine Laurent Lavoisier's oxygen-based chemistry
had been.
Atomic weights
Dalton proceeded to print his first published table of relative atomic weights. Six elements
appear in this table, namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus, with
the atom of hydrogen conventionally assumed to weigh 1. Dalton provided no indication in this
first paper how he had arrived at these numbers.[citation needed]However, in his laboratory notebook
under the date 6 September 1803[15] there appears a list in which he sets out the relative weights
of the atoms of a number of elements, derived from analysis of water, ammonia, carbon dioxide,
etc. by chemists of the time.
It appears, then, that confronted with the problem of calculating the relative diameter of the
atoms of which, he was convinced, all gases were made, he used the results of chemical
analysis. Assisted by the assumption that combination always takes place in the simplest
possible way, he thus arrived at the idea that chemical combination takes place between
particles of different weights, and it was this which differentiated his theory from the historic
speculations of the Greeks, such as Democritus and Lucretius.[citation needed]
The extension of this idea to substances in general necessarily led him to the law of multiple
proportions, and the comparison with experiment brilliantly confirmed his deduction.[16] It may be
noted that in a paper on the proportion of the gases or elastic fluids constituting the atmosphere,
read by him in November 1802, the law of multiple proportions appears to be anticipated in the
words: "The elements of oxygen may combine with a certain portion of nitrous gas or with twice
that portion, but with no intermediate quantity", but there is reason to suspect that this sentence
may have been added some time after the reading of the paper, which was not published until
1805.
Compounds were listed as binary, ternary, quaternary, etc. (molecules composed of two, three,
four, etc. atoms) in the New System of Chemical Philosophy depending on the number of atoms
a compound had in its simplest, empirical form.
He hypothesized the structure of compounds can be represented in whole number ratios. So,
one atom of element X combining with one atom of element Y is a binary compound.
Furthermore, one atom of element X combining with two elements of Y or vice versa, is a ternary
compound. Many of the first compounds listed in the New System of Chemical
Philosophy correspond to modern views, although many others do not.
Various atoms and molecules as depicted in John Dalton's A New System of Chemical
Philosophy (1808).
Dalton used his own symbols to visually represent the atomic structure of compounds. These
were depicted in theNew System of Chemical Philosophy, where Dalton listed twenty elements
and seventeen simple molecules.
Other investigations
Dalton published papers on such diverse topics as rain and dew and the origin of springs
(hydrosphere); on heat, the color of the sky, steam, and the reflection and refraction of light; and
on the grammatical subjects of the auxiliary verbs and participles of the English language.
Experimental approach
As an investigator, Dalton was often content with rough and inaccurate instruments, even
though better ones were obtainable. Sir Humphry Davy described him as "a very coarse
experimenter", who almost always found the results he required, trusting to his head rather than
his hands. On the other hand, historians who have replicated some of his crucial experiments
have confirmed Dalton's skill and precision.
In the preface to the second part of Volume I of his New System, he says he had so often been
misled by taking for granted the results of others that he determined to write "as little as possible
but what I can attest by my own experience", but this independence he carried so far that it
sometimes resembled lack of receptivity. Thus he distrusted, and probably never fully
accepted, Gay-Lussac's conclusions as to the combining volumes of gases.
He held unconventional views on chlorine. Even after its elementary character had been settled
by Davy, he persisted in using the atomic weights he himself had adopted, even when they had
been superseded by the more accurate determinations of other chemists.
He always objected to the chemical notation devised by Jöns Jakob Berzelius, although most
thought that it was much simpler and more convenient than his own cumbersome system of
circular symbols.
Other publications
For Rees's Cyclopædia Dalton contributed articles on Chemistry and Meteorology, but the topics
are not known.
He contributed 117 Memoirs of the Literary and Philosophical Society of Manchester, from 1817
until his death in 1840, while president of that organization. Of these the earlier are the most
important. In one of them, read in 1814, he explains the principles of volumetric analysis, in
which he was one of the earliest workers. In 1840 a paper on the phosphates and arsenates,
often regarded as a weaker work, was refused by the Royal Society, and he was so incensed
that he published it himself. He took the same course soon afterwards with four other papers,
two of which (On the quantity of acids, bases and salts in different varieties of salts and On a
new and easy method of analysing sugar) contain his discovery, regarded by him as second in
importance only to the atomic theory, that certain anhydrates, when dissolved in water, cause no
increase in its volume, his inference being that the salt enters into the pores of the water.
Public life
Before he had propounded the atomic theory, he had already attained a considerable scientific
reputation. In 1803, he was chosen to give a course of lectures on natural philosophy at
the Royal Institution in London, and he delivered another course of lectures there in 1809–1810.
However, some witnesses reported that he was deficient in the qualities that make an attractive
lecturer, being harsh and indistinct in voice, ineffective in the treatment of his subject, and
singularly wanting in the language and power of illustration.
In 1810, Sir Humphry Davy asked him to offer himself as a candidate for the fellowship of the
Royal Society, but Dalton declined, possibly for financial reasons. However, in 1822 he was
proposed without his knowledge, and on election paid the usual fee. Six years previously he had
been made a corresponding member of the French Académie des Sciences, and in 1830 he
was elected as one of its eight foreign associates in place of Davy. In 1833, at age 67 Earl
Grey's government conferred on him a pension of £150, raised in 1836 to £300. He was elected
a Foreign Honorary Member of the American Academy of Arts and Sciences in 1834 at age
68.[17]
A young James Prescott Joule, who later studied and published (1843) on the nature of heat
and its relationship to mechanical work, was a famous pupil of Dalton in his last years.
Personal life
Dalton in later life by Thomas Phillips, National Portrait Gallery, London (1835).
Dalton never married and had only a few close friends. All in all as a Quaker he lived a modest
and unassuming personal life.[1]
For the twenty-six years prior to Dalton's death, he lived in a room in the home of the Rev. (and
Mrs.) W. Johns, a published botanist, in George Street, Manchester. Dalton and Johns died in
the same year - 1844.
Dalton's daily round of laboratory work and tutoring in Manchester was broken only by annual
excursions to the Lake District and occasional visits to London. In 1822 he paid a short visit to
Paris, where he met many distinguished resident men of science. He attended several of the
earlier meetings of the British Association at York, Oxford, Dublin and Bristol.
Disability and death
Bust of Dalton by Francis Legatt Chantrey, 1854
Dalton suffered a minor stroke in 1837, and a second one in 1838 left him with a speech
impairment, though he remained able to perform experiments. In May 1844 he had yet another
stroke; on 26 July 1844 he recorded with trembling hand his last meteorological observation. On
27 July 1844, in Manchester, Dalton fell from his bed and was found lifeless by his attendant.
Dalton was accorded a civic funeral with full honours. His body was laid in state in Manchester
Town Hall for four days and more than 40,000 people filed past his coffin. The funeral
procession included representatives of the city’s major civic, commercial, and scientific
bodies.[18][19] He was buried in Manchester in Ardwick cemetery. The cemetery is now a playing
field, but pictures of the original grave may be found in published materials.[20][21]
Legacy
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A bust of Dalton, by Chantrey, was publicly subscribed for[22] and placed in the entrance hall
of the Royal Manchester Institution. Chantrey also crafted a large statue of Dalton: it was
erected while Dalton was still alive and it has been said: "He is probably the only scientist
who got a statue in his lifetime".[19] It was placed in Manchester Town Hall after its
construction in 1877 and remains there today.
In honour of Dalton's work, many chemists and biochemists use the (as yet unofficial)
designation dalton (abbreviated Da) to denote one atomic mass unit (1/12 the weight of a
neutral atom of carbon-12).
There is a John Dalton Street connecting Deansgate and Albert Square in the centre of
Manchester.
Manchester Metropolitan University named a building after John Dalton; it is occupied by the
Faculty of Science and Engineering. A statue of Dalton, the work of William Theed, was
erected in Piccadilly in 1855, and moved in 1966 to outside this building.
Statue of Dalton, by Francis Leggatt Chantrey in the Manchester Town Hall.

The University of Manchester has a hall of residence called Dalton Hall; it also established
two Dalton Chemical Scholarships, two Dalton Mathematical Scholarships, and a Dalton
Prize for Natural History. There is a Dalton Medal, awarded thus far only twelve times by the
Manchester Literary and Philosophical Society.

Dalton Township in southern Ontario was named for Dalton. It 2001 the name was lost when
the township was absorbed into the City of Kawartha Lakes; however in 2002 the Dalton
name was affixed a massive new park there: Dalton Digby Wildlands Provincial Park.
 A lunar crater was named after Dalton.
 "Daltonism" became a common term for colour blindness and "Daltonien" is the actual
French word for "colour blind".
 The inorganic section of the UK's Royal Society of Chemistry is named after Dalton (Dalton
Division), and the Society's academic journal for inorganic chemistry also bears his name
(Dalton Transactions).
 Many Quaker schools name buildings after Dalton: for example, one of the school houses in
Coram House, the primary sector of Ackworth School, is called Dalton.
 Much of his written works were collected at the Manchester Literary and Philosophical
Society, but were damaged during a bombing on 24 December 1940. This event
prompted Isaac Asimov to say, "John Dalton's records, carefully preserved for a century,
were destroyed during the World War II bombing of Manchester. It is not only the living who
are killed in war". The damaged papers are now in the John Rylands Library.
The standard author abbreviation Jn.Dalton is used to indicate this individual as the author
when citing a botanical name.[23]