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Chem 106, Prof. J.T. Spencer
Chapter 2: Atoms, Molecules and Ions
 What
1
is Chemistry
Logic
Magic
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Atoms, Molecules and Ions
 Science:
2
Atomic Theory
– “The
strength of a science is that its conclusions
are derived by logical arguments from facts that
result from well-designed experiments. Science
has produced a picture of the microscopic
structure of the atom so detailed and subtle of
something so far removed from our immediate
experience that it is difficult to see how its many
features were constructed. This is because so
many experiments have contributed to our ideas
about the atom.”
B. Mahan from University Chemistry
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
3
Atoms, Molecules and Ions
Science:
Atomic Theory
– from a fundamental understanding of the
macroscopic behavior of substances comes an
understanding the microscopic behavior of
atoms and molecules (Baseball rules from Baseball Game?)
Macroscopic
Substances
Mixtures
Physical Properties and Changes
Microscopic
Atomic theory
Question: Can matter be infinitely divided?
Most Greek Philosophers - Yes
Democritus (460 BC) and John Dalton (1800s) - No (“atomos”means indivisible”)
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
4
Atoms, Molecules and Ions
 History
of Atomic Theory and Scientific Inquiry
– Aristotle - “metaphysics”,
thought experiments and
no experimental observations
necessary to substantiate ideas.
– Archimedes (287 - 212 BC) - Scientific Method,
determined composition of the King of
Syracuse’s crown by measuring density
through water displacement.
– Roger Bacon (1214 - 1294) - Experimental
Science “ It is the credo of free men - the
opportunity to try, the privilege to err, the
courage to experiment anew. ...experiment,
experiment, ever experiment”.
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Archimedes (287-212BC)
 Archimedes
5
was a native of Syracuse (not
NY). Stories from Plutarch, Livy, and
others describe machines invented by
Archimedes for the defence of Syracuse
(These include the catapult, the compound
pulley and a burning-mirror).
 Archimedes discovered fundamental
theorems concerning the centre of gravity
of plane figures and solids. His most
famous theorem gives the weight of a body
immersed in a liquid, called Archimedes'
principal.
His methods anticipated integral calculus 2,000 years before
Newton and Leibniz.
Chem 106, Prof. J.T. Spencer
Archimedes (287-212BC)
6
Chem 106, Prof. J.T. Spencer
Archimedes (287-212BC)
7
Suspecting that a goldsmith might have replaced some of the gold by silver in
making a crown, Hiero II, the king of Syracuse, asked Archimedes to determine
whether the wreath was pure gold. The wreath could not be harmed since it was a
holy object.
The solution which occurred when he stepped into his bath and caused it to overflow
was to put a weight of gold equal to the crown, and known to be pure, into a bowl
which was filled with water to the brim. Then the gold would be removed and the
king's crown put in, in its place. An alloy of lighter silver would increase the bulk of
the crown and cause the bowl to overflow.
Pure Gold?
Equal Weight of Gold
Crown Displaced More Water
Chem 106, Prof. J.T. Spencer
8
Greek Philosophers
Fire
Air
Greek “Elements”
Water
Earth
Democratus - First to say that all matter is
NOT infinately divisible. [But the
Greeks did not test their ideas]
Alchemy - Pseudoscience by fakes and mystics
devoted to turning base metals to gold BUT they
did make (by accident) many ground breaking
discoveries of nature (chemical reactions).
Chem 106, Prof. J.T. Spencer
Scientific Measurement
9
Robert Boyle - Robert Boyle
(1627-1691) was born in Ireland.
He became especially interested in
experiments involving air and
developed an air pump with which
he produced evacuated cylinders.
He used these cylinders to show
that a feather and a lump of lead fall
at the same rate in the absence of air
resistance. In his book “The Sceptical Chemist” (1661),
Boyle urged that the ancient view of elements as
mystical substances should be abandoned and that an
element should instead be defined as anything that
cannot be broken down into simpler substances.
Chem 106, Prof. J.T. Spencer
10
Scientific Measurement
Antoine
Lavoisier (1743 - 1794) -
Furthered measurement as basis for
scientific reasoning.
– “Je Veux Parler Des Faits” - Do Not Rely
Upon Speculation But Build Upon Facts.
More on Lavoisier on Next Slide
Chem 106, Prof. J.T. Spencer
Antoine Lavoisier
11
Antoine Lavoisier was born in
Paris, and although Lavoisier's
father wanted him to be a
lawyer, Lavoisier was
fascinated by science. From the
beginning of his scientific
career, Lavoisier recognized the
importance of accurate
measurements. He wrote the first modern chemistry (1789)
textbook so that it is not surprising that Lavoisier is often called the
father of modern chemistry. To help support his scientific work,
Lavoisier invested in a private tax-collecting firm and married the
daughter of one of the company executives. Guillotined for his tax
work in 1794.
Chem 106, Prof. J.T. Spencer
12
Atoms, Molecules and Ions
Atomic Theory and Scientific Inquiry
– Lavoisier (1743 - 1794) - founder of “modern
chemistry”, not to rely on speculation but to
build upon facts, ended the “time of alchemy”.
Earth
 History
pure water
Alchemy
Water
evaporate out water from
dust sealed container
Law of Conservation of Mass
Fire
“earth”
alchemists said that the water
was “transmuted” to earth
Lavoisier showed that the amount of “earth” found at the
end of the experiment was equal to the weight the container
lost, therefore, the water was not “transmuted” to earth.
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
13
Scientific Method
Form and test
hypothesis
Patterns and
Trends
Theory
Observations
and Experiments
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
John Dalton (1766-1844)
14
John Dalton (1766 -1844), an
Englishman, began teaching school
when he was 12. He was fascinated
with meteorology (keeping daily
weather records for 46 years), which
led to an interest in gases and their
components, atoms. He switched to
chemistry when he saw applications in
chemistry for his ideas about the atmosphere. He proposed
the Atomic Theory in 1803. Dalton was a humble man with
several apparent handicaps: he was poor; he was not
articulate; he was not a skilled experimentalist, and he was
color-blind (a terrible problem for a chemist). In spite of these
disadvantages he did great things.
Chem 106, Prof. J.T. Spencer
15
Atomic Theory
John
Dalton’s Atomic Theory
–Designed a theory to account for a variety
of experimental observations:
–Each element is composed of extremely
small particles (called atoms).
–All atoms of a given element are
identical (therefore, atoms of different
elements are different and have
different properties).
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
16
Atomic Theory (Continued)
John
Dalton’s Atomic Theory
–Atoms of an element are not changed
into different types of atoms by
chemical reactions and atoms are
neither created nor destroyed in
chemical reactions.
–Compounds are formed when atoms
combine and a given compound always
has the same relative number and kind
of atoms.
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Atomic Theory
17
Dalton’s
Atomic Theory
–Atoms are the building blocks:
–Elements are composed of only one
kind of atom.
–Compounds are made by mixing atoms
in definite proportions
–Mixtures do not involve the type of
“small scale” (but strong) interactions
found in Elements and Compounds
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
18
Atomic Theory; Dalton’s Theories
 Law
of Constant Composition (or Definite
Proportion, first proposed by Joseph Proust):
– In any given compound, the relative number
and kind of atoms are constant (same
proportion of elements by mass).
–implies that atoms interact in a specific
way when they form a compound.
–the elements making up a particular
compound combine in the same
proportions regardless of the manner in
which the compound was prepared.
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
19
Atomic Theory; Dalton’s Theories
 Law
of Constant Composition (or Definite
Proportion):
Copper Carbonate ALWAYS contains 5.3 parts
Copper to 4 parts Oxygen and 1 part Carbon (by
Weight).
Carbon Dioxide ALWAYS contains 1.00 parts
Carbon to 2.67 parts Oxygen
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Atomic Theory; Dalton’s Theories
20
 Law
of Conservation of Mass:
– the total amount of material present after a
chemical reaction is the same as the amount
present before the reaction.
Matter (elements, etc...) cannot be created nor
destroyed during chemical reactions.
Total Mass
Before
Chemical
Reaction
=
Total Mass
After
Chemical
Reaction
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
21
Guy-Lussac
Joseph Guy-Lussac (1778 - 1850) found that (at the
same temperatures and pressures):
2 volumes of hydrogen reacts with 1 volume of
oxygen to yield 1 volume of water vapor
O
+
H
=
Water
Amedeo Avogadro (1776 - 1856) proposed that (at the
same temperatures and pressures), equal volumes of
different gases contain the same number of particles:
2 molecules of H + 1 molecule of O yield 1 molecule of water
Chem 106, Prof. J.T. Spencer
Experiments in Atomic Theory
22
Dalton’s Laws Set Groundwork for Atomic Theory but
Important Experiments Lead to Our Modern
Understanding
Faraday
- Electrodeposition
Millikan - Oil Drop Experiment
Roetgen - Radioactivity
Curie - Radioactive Particles
Rutherford - Gold Foil Experiment
Chem 106, Prof. J.T. Spencer
Michael Faraday (1791-1867)
23
Experiments in electromagnetism, electrical power
conversion, etc...
Humble scientist rose from
very poor background to
become one of the most
influential of his age. Believed
that careful observations were
most important.
“Try desperately to succeed and do not hope for success”
Chem 106, Prof. J.T. Spencer
24
Atomic Structure
Electrical
Nature
–Michael Faraday (1833) (first
ideas about the nature of
electricity
–The weight of a material
deposited at an electrode by a
given amount of electricity is
always the same.
–The weights of various
materials deposited by fixed
amounts of electricity are
proportional to their
equivalent weights. [remember
equivalent weights]
Electrodeposition
Cell
electrodes
- +
deposition
electrolyte
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Sir J. J. Thomson
25
British physicist who
worked with electrical
currents and fields.
Appointed Prof. of Physics
at Cambridge when
he was 27 and
Received the Nobel
Proze in
1906 for his
characterization
of
the electron.
Chem 106, Prof. J.T. Spencer
26
Atomic Structure
J.
J. Thomson: Cathode Ray Tube (CRT) Experiment
– Set up a large electrical potential between a pair of
electrodes in a glass tube and an electrical current will
flow between the elctrodes.
–The current will flow even when all the air is pumped
out of the tube. The invisible charge carriers were called
“cathode rays”.
–Cathode rays travel in straight lines and form a
luminious spot when they hit a glass tube.
(-)
(+)
Cathode Ray Tube
[evacuated glass tube]
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
27
Atomic Structure: CRT
The cathode rays
are deflected by an
electric field.
(-)
(+)
Electric Field
The cathode rays are
deflected by an
magnetic field.
(-)
The same effect was observed
regardless of what gas was used in the
discharge tube. Therefore, electricity
must be a universal fragment.
(+)
Magnetic Field
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Electricity: Thomson’s charge to mass
(-)
CRT
(+)
(-)
Magnetic Field
28
1
2
3
(+)
Electric Field
Spot
mag field
1
3
2
On
Off
Off
On
elec. field
Off
On
Off
On
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Thomson’s charge to mass
29
Ee = Electrical Field
He = Magnetic Field
[where e = electric charge (unk) and  = velocity]
Set up experiment such that;
Electrical Field = Magnetic Field
Ee = He
or
E / H
Now, turn off the mag. field and measure deflection of beam ()
Using Newton’s 2nd Law can calculate e/m
CRT
(-)
(-)
Magnetic Field
(+)
(+)
1
2
3
Chem 106, Prof. J.T. Spencer
Thomson’s charge to mass
30
calculated charge to mass ratio (e/m)
for electron = 1.76 x 108 coulombs/g
found;
(1) e/m was 1000x greater than for any known ion
(2) e/m of independent of gas in tube [Universal Fragment]
(3) Not electrified atoms but fragments (called electrons)
Chem 106, Prof. J.T. Spencer
Robert Millikan (1868-1953)
31
Nobel Prize, 1923; for his work on
the elementary charge of electricity
and on the photoelectric effect.
Robert Millikan was one of
the first American scientists to be
recognized in Europe. In 1909 he
performed the first of a series of
experiments to measure the
fundamental charge of an electron,
the Millikan Oil Drop Experiment.
The value determined by this experiment was used in Bohr's
formula for the energy of the Hydrogen line spectrum as a first
confirmation of the quantized atom. He named and studied
"cosmic rays" as well.
Chem 106, Prof. J.T. Spencer
Electricity: Millikan’s electron mass
32
Oil Drop Experiment (1909)
atomizer
-
high
voltage
+
viewer
Ionization by radiation causes
the oil to pick up “extra” electrons
Goal: to measure the electrical
charge on each oil droplet
Procedure: measure the velocity of
the falling oil drop both with
and without the high voltage
plates urned on
Found: charges were always
multiples of 1.60 x 10-19 C
Postulate: charge of one electron
was 1.60 x 10-19 C
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
33
Electricity: electron mass
Thomson
Millikan
charge =
mass
e =
m
charge = e
1.76 x 108 coul g-1
= 1.60 x 10-19 coul
Combine and Solve
mass =
charge
= 1.60 x 10-19 C = 9.10 x 10-28 g
1.76 x 108 coul g-1 1.76 x 108 C g-1
mass of the electron was 2000x smaller than the
lightest atom (hydrogen)
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
Wilhelm Conrad Roentgen
Wilhelm Conrad
Roentgen
34
Wilhelm Conrad Roentgen was born in
Lennep, Germany, on 27 March 1845. He
obtained a degree in mechanical
engineering and, in 1869, was awarded a
degree in physics. While working as a
professor of physics at Wurzburg
University, he made his famous discovery.
He called the unknown radiation "X rays,"
since "X" frequently stands for an
unknown quantity in mathematics. His
unique discovery truly changed the world
and immediately became a useful tool for
medical science.
Chem 106, Prof. J.T. Spencer
Radioactivity:
35
Wilhelm Roetgen and Henri Becquerel
metal
target
CRT
e beam
invisible
radiation
(X-rays)
U
X-rays
- not affected by magnetic fields
- passed thru many materials
-produced images on film
(ionized Ag emulsions)
glowed in dark (phosphorescence)
emitted high energy
radiation in the dark (radioactivity)
Chapt. 2.1
Chem 106, Prof. J.T. Spencer
1903 Nobel Prize for Radioactivity
Pierre and Marie Curie
Henri Becquerel
36
Chem 106, Prof. J.T. Spencer
Marie Sklodawaska Curie
37
The most famous of all women scientists, Marie
Sklodowska-Curie is notable for many firsts.
In 1903, she became the first woman to win a
Nobel Prize for Physics (Pierre Curie
and Henri Becquerel, for the discovery
of radioactivity.
She was also a professor at the Sorbonne
University in Paris (1906).
In 1911, she won an unprecedented second
Nobel Prize (in chemistry for her
discovery radium. She was the first
person ever to receive two Nobel
Prizes.)
Marie Sklodowska-Curie She was the first mother of a Nobel Prize
In 1934, Maria Curie died of leukemia
Laureate; daughter- Nobel Prize 1932.
Chem 106, Prof. J.T. Spencer
38
Radioactivity: Marie Curie and Ernest Rutheford
 Marie
Curie (1867 - 1934) - separated the pure
radioactive material (Uranium) which was
spontaneously radioactive (from the mineral
pitchblende)
 Ernest Rutheford (1871 - 1937) - found radiation
from uranium was of three types (, , and )


U
+

 - heavy particles with +2 charge, combines with electrons
to form helium, 4He
 - electrons with -1 charge
Chapt. 2.1
 - high energy electromagnetic radiation
slits
Chem 106, Prof. J.T. Spencer
39
Nuclear Atom: Thomson’s Model (ca. 1900)
 Since
the electron made up only a small amount of
an atom’s mass it was proposed that it must
similarly make up a small amount of the atoms
volume.
“Plum-pudding” model
positive charge spread
over sphere
= electron
Chem 106, Prof. J.T. Spencer
Ernest Rutherford
40
Ernest Rutherford (1871-1937) was
born on a farm in New Zealand. In
1895 he placed second in a
scholarship competition to attend
Cambridge University, but was
awarded the scholarship when the
winner decided to stay home and get
married. As a scientist in England,
Rutherford did much of the early
work on characterizing
radioactivity. He also invented the
name proton for the nucleus of the hydrogen atom. He received
the Nobel Prize in chemistry in 1908.
Chem 106, Prof. J.T. Spencer
Nuclear Atom: Rutheford and the Gold Foil

4He
particles
slits
thin
gold
foil

41
experiment - fired
heavy  particles
at a thin gold foil
and looked
for deflections
detector
found - most particles passed straight through foil, some had
deflections thru small angles BUT some had VERY
large deflections ( = 180°)
“...as if you fired a 15-inch
cannon shell at a piece of tissue
paper and it came back and hit you...”
Chem 106, Prof. J.T. Spencer
Nuclear Atom: Rutheford and the Gold Foil
A:C around 13,000:1
 Beam
A
A
C
B
B
A
A
Gold Foil
42
Chem 106, Prof. J.T. Spencer
Rutheford’s Atom
Based on gold foil experiment and previous work
with electrical and nuclear particles, proposed a
nuclear theory;
(1) atoms are mostly empty space with very dense
(pos. charged) nuclear core (<10-12 cm dia.)
(2) atoms are highly “non-uniform”
(3 ) atomic nucleus must contain large electrical
forces of considerable mass (since small electron
cannot be responsible for such large deflections)
43
Chem 106, Prof. J.T. Spencer
Nature’s Basic Forces
44
 Electromagnetic
- force between charged or
magnetic particles (electrical and magnetic forces
+
- are very closely related).
DRIVES MOST OF CHEMICAL
BEHAVIOR (Coulomb’s Law; F = kQ1Q2/d2)
 Gravitational - force between objects proportional
m
m to their masses.
 Strong Nuclear - force keeping like charged
nucleons (such as protons) together
+
+ +
(very strong but very short range).
+
 Weak Nuclear - nuclear force observed in some
radioactive behavior (weaker than electromagnetic
but stronger than gravitational).
Strong Nucl. > Electromagnetic > Weak Nucl. > Gravitational
Chem 106, Prof. J.T. Spencer
Modern Atomic Structure
45
dimensions; nucleus 10-4 Å and atom 1 - 2 Å
(1 Å = 10-10 m) “... if a nucleus were 2 cm (ca. 1 in.)
then the atom would be 200 m (ca. 200 yds)”
 atom composed of many “subatomic” particles but only
three of these are important to chemists
 atomic mass (1 amu = 4 x 10-22 g), charge
(1 esc = 1.60 x 10-19 coul), density (1014 g/cm3)
 atom = dense nucleus with mostly empty space; electrons of
most chemical import. (matchbox of nucl. = 2.5 billion tons)
 atomic
particle
proton
neutron
electron
charge (esu)
+1
0
-1
mass (amu)
1.0073
1.0087
5.486 x 10-4
Chem 106, Prof. J.T. Spencer
46
Atomic Theory: Isotopes
 differences/similarities
between atoms of an element;
all atoms of an given element have the same number
of protons (and therefore the same number of
electrons to balance charge)
atoms of an element may have different numbers of
neutrons - called isotopes
AE
Z
11C
6
12C
6
13C
6
14C
6
atomic number (Z) - number of protons
mass number (A) - number of protons + number of neutrons
nuclide - atoms of a specific elemental isotope
Chem 106, Prof. J.T. Spencer
47
Atomic Theory: Isotopes
14N
7
electrons, 7 protons, 7 neutrons
17O
8
electrons, 8 protons, 9 neutrons
35Cl
 17
electrons, 17 protons, 18 neutrons
238U
 92
electrons, 92 protons, 146 neutrons
7
8
17
92
Chem 106, Prof. J.T. Spencer
48
Atomic Theory: Isotopes
Sample exercise:How many protons, neutrons,
and electrons are in a 39K atom?
Chem 106, Prof. J.T. Spencer
49
Atomic Theory: Isotopes
Sample exercise:How many protons, neutrons,
and electrons are in a 39K atom?
Atomic# = 19
# of protons = 19
# of electrons = 19
Mass # = 39
39 - 19 = 20 neutrons
Chem 106, Prof. J.T. Spencer
50
Atomic Theory: Isotopes
Sample exercise:Give the complete chemical
symbol for the nuclide that contains 18
protons, 18 electrons, and 22 neutrons.
Chem 106, Prof. J.T. Spencer
51
Atomic Theory: Isotopes
Sample exercise:Give the complete chemical
symbol for the nuclide that contains 18
protons, 18 electrons, and 22 neutrons.
Atomic # = 18 , element is Argon
Chem 106, Prof. J.T. Spencer
52
Atomic Theory: Isotopes
Sample exercise:Give the complete chemical
symbol for the nuclide that contains 18
protons, 18 electrons, and 22 neutrons.
Atomic # = 18 , element is Argon
40Ar
18
Chem 106, Prof. J.T. Spencer
53
Atomic Theory: Isotopes
 Allotropes
- Different chemical forms of the same
element existing in the same physical state.
Fullerene
Graphite
Diamond
Chem 106, Prof. J.T. Spencer
54
Periodic Table; Dmitri Mendeleev (1869)
 Displays
chemical reactivity trends and
relationships and constructed to account for
(and predict) chemical reactivity of the
elements.
For example:
Li, Na, K
soft metals, v. reactive w/
water
He, Ne, Ar gases and not reactive
F, Cl, Br reactive with many other
elements in a similar
fashion
Cu, Ag, Au Metal w/ similar reactivity
Chem 106, Prof. J.T. Spencer
Periodic Table; Dmitri Mendeleev
55
Chem 106, Prof. J.T. Spencer
56
Periodic Table
1
2
16
17
18
Group
or Family
1
2
3
4
5
6
Alkali metals
Alkaline earth metals
Chalcogens (chalk formers)
Halogens (salt formers)
Noble Gases (inert gases)
7
8
9
10
11
12
13
14
15
Li, Na, K,...
Be, Mg, Ca,...
O, S, Se,...
F, Cl, Br,...
He, Ne, Ar,...
16
17
1H
Row
18
2 He
3 Li
4 Be
5B
6C
7N
8O
9F
10 Ne
11 Na
12 M g
13 Al
14 Si
15 P
16 S
17 Cl
18 Ar
19 K
20 Ca
21 Sc
22 Ti
23 V
24 Cr
25 M n
26 Fe
27 Co
28 Ni
29 Cu
30 Zn
31 Ga
32 Ge
33 As
34 Se
35 Br
36 Kr
37 Rb
38 Sr
39 Y
40 Zr
41 Nb
42 M o
43 Tc
44 Ru
45 Rh
46 Pd
47 Ag
48 Cd
49 In
50 Sn
51 Sb
52 Te
53 I
54 Xe
55 Cs
56 Ba
57 La
72 Hf
73 Ta
74 W
75 Re
76 Os
77 Ir
78 Pt
79 Au
80 Hg
81 Tl
82 Pb
83 Bi
84 Po
85 At
86 Rn
87 Fr
88 Ra
89 Ac
104 Unq 105 Unp 106 Unh 107 Ns
108 Hs
109 M t
58 Ce
59 Pr
60 Nd
61 Pm
62 Sm
63 Eu
64 Gd
65 Tb
66 Dy
67 Ho
68 Er
69 Tm
70 Yb
71 Lu
90 Th
91 Pa
92 U
93 Np
94 Pu
95 Am 96 Cm
97 Bk
98 Cf
99 Es
100 Fm 101 Md 102 No
103 Lr
Chem 106, Prof. J.T. Spencer
57
Periodic Table
alkali metals
alkaline earth metals
1
2
3
4
5
1H
6
7
8
9
10
non-metals
noble gases
metalloids
11
13
14
15
16
17
18
2 He
metals
5B
6C
7N
8O
9F
10 Ne
13 Al
14 Si
15 P
16 S
17 Cl
18 Ar
30 Zn
31 Ga
32 Ge
33 As
34 Se
35 Br
36 Kr
47 Ag
48 Cd
49 In
50 Sn
51 Sb
52 Te
53 I
54 Xe
78 Pt
79 Au
80 Hg
81 Tl
82 Pb
83 Bi
84 Po
85 At
86 Rn
69 Tm
70 Yb
71 Lu
3 Li
4 Be
11 Na
12 M g
19 K
20 Ca
21 Sc
22 Ti
23 V
24 Cr
25 M n
26 Fe
27 Co
28 Ni
29 Cu
37 Rb
38 Sr
39 Y
40 Zr
41 Nb
42 M o
43 Tc
44 Ru
45 Rh
46 Pd
55 Cs
56 Ba
57 La
72 Hf
73 Ta
74 W
75 Re
76 Os
77 Ir
87 Fr
88 Ra
89 Ac
104 Unq 105 Unp 106 Unh 107 Ns
108 Hs
109 M t
rare earth
metals
12
58 Ce
59 Pr
60 Nd
61 Pm
62 Sm
63 Eu
64 Gd
65 Tb
66 Dy
67 Ho
68 Er
90 Th
91 Pa
92 U
93 Np
94 Pu
95 Am 96 Cm
97 Bk
98 Cf
99 Es
100 Fm 101 Md 102 No
103 Lr
Chem 106, Prof. J.T. Spencer
58
Periodic Table (1869)
metals
non-metals
conductors
shiny
high thermal conductivity
solids at RT
ductile
insulators
dull
thermal insulators
freq. non-solids at RT
brittle
Metalloids (along line in table) have properties
between metals and non-metals
Chem 106, Prof. J.T. Spencer
Molecules and Ions
- “assembly” of two or more atoms (with
properties different from constituent types of
atoms (see “Law of Multiple Proportions”). i.e.,
H2O, H2O2, CaCO3, HNO3, H2SO4,...
some elements found in nature as molecules
(i.e., O2, N2, etc... [diatomic])
 Formulas
Molecular - actual numbers and types of
atoms in a molecule
Empirical - smallest whole number ratio of
constituentStructural - “picture” showing
how the atoms are attached to one another
 Molecule
59
Chem 106, Prof. J.T. Spencer
60
Molecules
Molecular
Formula
Empirical
Formula
Structural
Formula
O
H2O (water)
H2O2
C2H4
(hydr. peroxide)
H
H2O
HO
H
H
O
O
H
H
(ethylene)
CH2
H
C
C
H
H
CH2 OH
C6H12O6 (glucose)
CH2O
H
O
H
OH
H
H
OH
OH
H
OH
Chem 106, Prof. J.T. Spencer
Formulas
 Ethylene
is a gas at room temperature and is the
starting material for for many plastics. Its
molecular formula is C2H4.
– What is its empirical formula?
– What other molecular formulas are
possible for this same empirical formula?
61
Chem 106, Prof. J.T. Spencer
62
Formulas
 Ethylene
is a gas at room temperature and is the
starting material for for many plastics. Its
molecular formula is C2H4.
– What is its empirical formula?
CH2
– What other molecular formulas are
possible for this same empirical formula?
C2H4 , C3H6 , C4H8 , C5H10 , ...
Chem 106, Prof. J.T. Spencer
Formulas
 Cucurbituril
is a compound with cage-like
molecules big enough to surround and loosely trap
smaller molecules. It has the molecular formula
C36H36N24O12.
– What is its empirical formula?
63
Chem 106, Prof. J.T. Spencer
64
Formulas
 Cucurbituril
is a compound with cage-like
molecules big enough to surround and loosely trap
smaller molecules. It has the molecular formula
C36H36N24O12.
– What is its empirical formula?
C3H3N2O
Chem 106, Prof. J.T. Spencer
Formulas
Sample exercise: Give the empirical
formula for the substance whose
molecular formula is Si2H6.
65
Chem 106, Prof. J.T. Spencer
66
Formulas
Sample exercise: Give the empirical
formula for the substance whose
molecular formula is Si2H6.
SiH3
Chem 106, Prof. J.T. Spencer
67
Ions
atoms
can gain or lose electrons to
become charged (called ions)
positive ion = cation
negative ion = anion
Na (neutral has 11 electrons) can
easily lose 1 electron to become a
cation (Na+1)
Chem 106, Prof. J.T. Spencer
68
Ions
Polyatomic
ions; molecules with
charges.
i.e., NO3-1, SO4-2, PO4-3, etc...
chemical properties of ions may be
VERY different from similar neutral
species
Predicting charges on ions - use
periodic table (gain or lose electrons
to end up with the same number as
the nearest noble gas)
Chem 106, Prof. J.T. Spencer
69
3
Ions
4
5
6
7
8
9
10
11
12
13
+1 +2
14
15
16
17
-3 -2 -1
e
Mg
5B
6C
7N
8O
9F
13Al
14Si
15P
16S
17C
Ca
21Sc
22Ti
23V
24Cr
25Mn
26Fe
27Co
28Ni
29Cu
30Zn
31Ga
32Ge
33As
34Se
35B
Sr
39Y
40Zr
41Nb
42Mo
43Tc
44Ru
45Rh
46Pd
47Ag
48Cd
49In
50Sn
51Sb
52Te
53I
Ba
57La
72Hf
73Ta
74W
75Re
76Os
77Ir
78Pt
79Au
80Hg
81Tl
82Pb
83Bi
84Po
85A
Ra
89Ac
104Unq
105Unp
106Unh
107Ns
108Hs
109Mt
58Ce
59Pr
60Nd
61Pm
62Sm
63Eu
64Gd
65Tb
66Dy
67Ho
68Er
69Tm
70Yb
71L
Chem 106, Prof. J.T. Spencer
70
Ions
Sample exercise: How many protons
and electrons does the Se2- ion
possess?
Chem 106, Prof. J.T. Spencer
71
Ions
Sample exercise: How many protons
and electrons does the Se2- ion
possess?
Se
atomic number = 34
# of protons = 34
# of electrons = 34 + 2 = 36
Chem 106, Prof. J.T. Spencer
72
Ionic Compounds
 transfer
of electrons between atoms,
Na + Cl = [Na]+[Cl] ionic compounds contain anions and cations, typically
combinations of metals and non-metals (molecular
compounds, in which electrons are shared, are usually
result from the combination of non-metals only); FeS,
LiBr, CuSO4, TiO4, etc...
 total charge is neutral; total (+) = total (-)
 ionic compounds are arranged in a 3D array (packing of
ping-pong balls)
 usually only empirical formulas can be written for ionic
compounds (because no real molecular unit in solid
phase but “extended” lattice)
 usually solids but soluble in water insol. in organic sols.
Chem 106, Prof. J.T. Spencer
73
Ionic Compounds
 total
charge is neutral; total (+) = total (-)
Cation
Anion
Charges
sodium (Na)
chlorine (Cl)
Na+1 + Cl-1
NaCl
magnesium(Mg) nitrogen (N)
aluminum (Al) bromine (Br)
Mg+2 + N-3
Al+3 + Br-1
Mg3N2
AlBr3
barium (Ba)
lithium (Li)
nickel (Ni)
Ba+2 + SO4-2
Li+1 + CO3-2
Ni+2 + Cl-1
Ni+3 + Cl-1
BaSO4
Li2CO3
NiCl2
NiCl3
sulfate (SO4)
carbonate (CO3)
chloride (Cl)
Empirical
Formula
Chem 106, Prof. J.T. Spencer
74
Ionic Compounds
+
-
+
+
+
-
-
+
-
-
+
+
-
-
+
+
+
-
+
-
+
-
+
-
+
-
+
-
-
-
+
Unit Cell
+
-
Cell Face
Chem 106, Prof. J.T. Spencer
75
Ionic Compounds
Sample exercise: Which of the following
compounds are molecular?
CI4
FeS
P4O6
PbF2
Chem 106, Prof. J.T. Spencer
76
Ionic Compounds
Sample exercise: Which of the following
compounds are molecular?
CI4
FeS
P4O6
PbF2
Chem 106, Prof. J.T. Spencer
77
Ionic Compounds
Sample exercise: Write the empirical
formulas for the compounds formed by
the following ions:
a) Na+ and PO43-
Chem 106, Prof. J.T. Spencer
78
Ionic Compounds
Sample exercise: Write the empirical
formulas for the compounds formed by
the following ions:
b) Zn2+ and SO42-
Chem 106, Prof. J.T. Spencer
79
Ionic Compounds
Sample exercise: Write the empirical
formulas for the compounds formed by
the following ions:
c) Fe3+ and CO32-
Chem 106, Prof. J.T. Spencer
80
Nomenclature: naming inorganic compounds
Method
for unambiguously referring to the
a. 15 million known molecules)
Organic compounds - containing C combined
typically with H, O, N, and S (originally
associated with living organisms but no
longer relevant definition)
Inorganic compounds - all other compounds
Chem 106, Prof. J.T. Spencer
81
Nomenclature: naming inorganic compounds
Traditional
names for compounds long
known (ammonia [NH3], water [H2O], Zeise’s
salt [Pt(C2H4)Cl3]-1], Muriatic Acid [HCl],
etc...)
common names (somewhat systematic,
ferrous chloride, cupric chloride, etc...)
International Union of Pure and Applied
Chemistry rules (IUPAC)
Chem 106, Prof. J.T. Spencer
82
Nomenclature: naming ionic compounds
 Ionic
compounds are names based upon the component ions.
 Positive ion (cation) named and written first
 Negative ion (anion) named and written last
 Solve ambiguity in charge by using Roman numerals
Cation
Anion
Compound
Na+
Al+3
Fe+2
ClO-2
O-2
NaCl
Al2O3
FeO
Name
sodium chloride
aluminum oxide
iron(II) oxide
(ferrous oxide)
Fe+3
O-2
Fe2O3
iron(III) oxide
(ferric oxide)
Chem 106, Prof. J.T. Spencer
83
Nomenclature: naming cations
 Monoatomic
- take the name from the element
» Li+1 lithium ion
» Ca+2 calcium ion
 Polyatomic
Sr+3
strontium ion
- only one common polyatomic cation
» NH4+1 ammonium ion
 Multiple
Cationic Charge Possible - specify charge with
Roman numerals to be unambiguous
» Fe+2 iron(II) ion
» Cr+6 chromium(VI) ion
Fe+3
Cr+5
iron(III) ion
chromium(V) ion
 For
metals, older method used to distinguish between ions
differing by one charge unit by adding suffix (-ous for lower
charge, -ic for higher charge)
» Fe+2 ferrous ion
» Co+2 cobaltous ion
Fe+3
Co+3
ferric ion
cobaltic ion
Chem 106, Prof. J.T. Spencer
84
Nomenclature: naming anions
 Monoatomic
» F-1
» O-2
 Polyatomic
- add -ide suffix
fluoride ion
oxide ion
P-3
B-5
phosphide ion
boride ion
- some common use -ide suffix
» OH-1 hydroxide ion
» N3-1 azide ion
CN-1
O2-2
cyanide ion
peroxide ion
 Oxyanions
- (1) when only two, the one with less oxygen ends
in -ite and the one with more oxygen ends with -ate
» NO2-1 nitrite ion
» SO3-2 sulfite ion
 Oxyanions-
NO3-1
SO4-2
nitrate ion
sulfate ion
for species with more than two members use
prefixes (hypo- less oxygen and per- more oxygen)
ClO-1
ClO2-1
ClO3-1
ClO4-1
hypochlorite
chlorite
chlorate
perchlorate
Chem 106, Prof. J.T. Spencer
85
Nomenclature: acids
- compound which yields H+ when dissolved in water
write hydrogen first; HCl, H2SO4, H3PO4, etc...
anions which end in -ide use hydro- as prefix and -ic as
suffix
Anion
Acid
Cl- (chloride)
HCl (hydrochloric acid)
F- (fluoride)
HF (hydrofluoric acid)
oxyacids - replace -ate suffix of anion with -ic,
replace -ite suffix of anion with -ous (leave prefixes!)
Anion
Acid
ClO2- (chlorite)
HClO2 (chlorous acid)
ClO3- (chlorate)
HClO3 (chloric acid)
ClO4-1 (perchloric) HClO4 (perchloric acid)
 Acid
Chem 106, Prof. J.T. Spencer
86
Nomenclature: molecular compounds
 Similar
to ionic compounds
– More positive element (left and down on
periodic table) named first (first in
Prefix Number
formula also)
Mono1
– Second element name ends with -ide
Di2
Tri3
– Use numbering prefixes if necessary
Formula
N2O5
IF7
XeO3
SiCl4
H2Se
P4O6
Name (text prob. 2.45)
dinitrogen pentoxide
iodine heptafluoride
xeon trioxide
silicon tetrachloride
dihydrogen selenide
tetraphosphorus hexoxide
TetraPentaHexaHeptaOctaNonaDeca-
4
5
6
7
8
9
10
Chem 106, Prof. J.T. Spencer
87
Nomenclature: examples
Formula
ZnCl2
(NH4)2SO4
FeF3
HBr
HBrO4
SF6
HCN
Name
 zinc(II)
chloride
 ammonium sulfate
 iron(III) fluoride
 hydrobromic acid
 perbromic acid
 sulfur hexafluoride
 hydrogen cyanide
Chem 106, Prof. J.T. Spencer
End Chapter 2
 Atomic
Theory
 Experiments leading to the discovery of atomic
structure
 The Periodic Table
 Molecules and Ions
 Nomenclature
88