Download Atomic Theory

Atomic Theory
Atomic Theories Timeline
Use a graphic organizer like this to record information
from this powerpoint and what you find online. You do
NOT have to include Jabir nor al –Ghazali.
Name
Democri
tus
Dalton
Can you think
of a candy
that would be
a good model
for the atom
according to
this scientist?
You only need
candy models
for: Democritus,
Dalton,
Thomson,
Rutherford,
Bohr, and
Schrodinger.
Time
Frame
Key
Points
Candy
Model
Thomson
Etc.
Earliest alchemists- 2500BC
The Egyptians were engaged
in practical chemistrymetallurgy, making dyes,
and producing glass. There
is no reference to an atom.
Kanada- India,
600BC
earliest recorded reference to
the idea of an atom that I
could find
Democritus
460 – 370 B.C.
• There are various basic
elements from which all
matter is made
• Everything is composed of
small atoms moving in a
void
• Some atoms are round,
pointy, oily, have hooks,
etc. to account for their
properties
• Ideas rejected by leading
philosophers because void =
no existence
Simplified model- what doesn’t
this show that makes his model
distinct from Dalton’s?
Video
Jabir- Arabic chemist of 8th
century
•
Considered one of the
fathers of experimental
chemistry but without
atomisim
Al-Ghazali in the
11th Century
revived Islamic science
Alchemy reigned in western Europe
John Dalton
1766-1844
• Introduced his ideas in 1803
• Each element is composed of
extremely small particles called
atoms
• All the atoms of a given element
are identical, but they differ from
those of any other element
• Atoms are neither created nor
destroyed in any chemical
reaction
• A given compound always has
the same relative numbers and
kinds of atoms
Dalton’s Theory
1. Elements are made of tiny, indivisible
particles (atoms).
Dalton’s Theory
2. An element’s atoms are identical and
unique to that element.
C=
N=
Ni =
Note that real atoms
are all basically the
same shape and
have no color.
Dalton’s Theory
3. Atoms combine chemically in simple
whole-number ratios.
No half -atoms.
Dalton’s Theory
4. Chemical reactions occur when atoms
separate, join, or rearrange. Atoms
CANNOT be changed into another atom.
(You can not make gold out of lead.)
+
+
+
+
Now go back and see if you can make a
distinction between Dalton’s and Democritus’
models.
J.J. Thomson
1856-1940
• Discovered electron
1897 – Cathode Ray
Experiment
• Plum Pudding model
1904
– Electrons in a soup of
positive charges
• Discovered isotopes
1913
JJ Thomson’s Ideas
Experiments with Cathode Ray
Tubes (late 1890s)
Cathode Ray Tube Experiment
Deflection of the “ray”
Evidence of the electron
Video
Thomson’s plum pudding
A real plum pudding
The Electron
• J.J. Thomson 1897 CRT experiment
• Negative Charge
• e• Actual Mass: 9.11 x
10-28g
• Relative mass: 1/1840
the mass of proton
(Millikan)
The Proton
• Goldstein 1886 - CRT
canal rays
• Positive charge
• p+
• Actual Mass: 1.67 x
10-24g
• Relative mass: 1
Ernest Rutherford
1871-1937
• Nucleus Theory 1910
– alpha particle gold foil
experiment
• An atom’s mass is
mostly in the nucleus
• The nucleus has a
positive charge
(Moseley)
• Electrons in fixed orbit
Gold Foil Experiment (1909)
Video
Rutherford’s atom
Nucleus with protons and “extra
mass”
Classic atom model
James Chadwick
1891-1974
• Worked with Rutherford
• Interpreted work of the
Curies
• Discovered Neutron 1932
• Nobel Prize in Physics
1935
Chadwick (1930)
Evidence of the Neutron
The Neutron
•
•
•
•
•
Chadwick 1932 - nuclear bombardment
No charge
n0
Actual Mass: 1.67 x 10-24g
Relative Mass: 1
Niels Bohr
1885-1962
• Planetary Model 1913
– Nucleus surrounded by
orbiting electrons at different
energy levels
– Electrons have definite orbits
• Utilized Planck’s Quantum
Energy theory
• Worked on the Manhattan
Project (US atomic bomb)
Bohr’s atom with energy levels
(1913)
Video
Bohr Model for Nitrogen
Pick A Candy!
Quantum mechanical model
• Bohr’s model was good for hydrogen, but
failed with atoms with more electrons
• Schrodinger used new experimental results
to come up with a mathematical equation
that explains electron behavior
• NO exact paths to follow- more of a cloud
where electrons may be found
• Video
Ernst Schrödinger 1887-1961
Werner Heisenberg 1901-1976
• Quantum Mechanical Model
1926
– Electrons are in probability
zones called “orbitals”, not
orbits and the location cannot
be pinpointed
– Electrons are particles and
waves at the same time
– Developed quantum numbers
based on theories of Einstein
and Planck
Schrodinger’s Model
• Electron probability map.
Quantum Mechanical Theory
Electron in a Hydrogen atom
Pick A
Candy!
Add two other players to this timeline- Millikan and
de Broglie. They are in your textbook.
Atomic Theory
JJ
Thomson
Democratus
400 BC
1803
John
Dalton
1904
Niels
Bohr
1910
Ernest
Rutherford
1913
1926
Schroedinger
/ Heisenberg
Energy levels
• Electrons can only be at certain energy
levels
• Quantum- amount of energy needed to
move from one energy level to the next
• Cannot stop between levels
Energy levels
• Not evenly spaced
• Higher energy levels are closer together.
• Higher energy levels are found further from
the nucleus.
Atomic orbitals
• A region of space where there is a high
probability of finding an electron
• Defined mathematically by Schrodinger
• Each orbital has a different shape
Orbital shapes
• s = spherical
• p= dumb bell on three axes
• d= like a double p on three axes and an odd
(one dumbbell with a donut)
• S, p, and d are also the names of the
sublevels
n = 2 orbitals
3d orbital photo