1/19 P. 2
Atomic Theory Notes
IQ: Which statement below best describes Charles
Darwin’s theory of natural selection and Alfred
Wegener’s theory of continental drift?
A. The theories answer all scientific questions about
evolution and continental drift.
B. The development of their theories was influenced
by many scientists.
C. Planned experiments were used to develop these
theories.
D. These theories are an example of how scientific
theories do not change over time.
ATOMS
What are they, & how do we
know they’re there?!
Under the IQ, draw what you think an
atom looks like inside a penny. Think
about its shape, relative size, and does
it have any smaller parts/pieces inside.
Atoms
• Basic unit of matter
• The smallest particle of a
substance that has all of its
properties.
• Called the ‘building blocks’ of
matter
• Example= the element Gold is
made of gold atoms; all exactly
the same, IF gold!!
1) Democritus - 460 BC
• First to develop the idea that matter was made
of particles called atoms.
• Atoms in different materials were of different
shapes/sizes which led to different properties.
Ex. Pepper atoms were spiky.
• The term “Atoms” comes from the Greek word
“atomos” (upto 1:06) which means “indivisible”
2) John Dalton - 1803
• Performed experiments with different
substances. Dalton’s work
i. Proposed atoms combine in specific proportions to
make new stuff- compounds.
ii. An atom is indivisible, indestructible, tiny sphere
iii. Atoms of the same element are exactly alike.
iv. Determined that elements have unique atomic
masses.
• OQ: Describe 2 ways that John Dalton’s
work/theory was different from Democritus’s,
1 way it was similar.
1/20 Atomic Theory cont’d
IQ: True or False?
1. Democritus believed that different atoms
combined to form new stuff.
2. Dalton stated that atoms of all elements were
exactly alike with equal masses.
3. Dalton believed that atoms could not be
further divided.
4. Democritus and Dalton both proposed that
atoms are tiny spheres.
3) Joseph John Thomson - 1898
• Discovered electrons through the use of a cathode ray
tube, proved that atoms were further divisible.
• Mass of e-s 1800 times lighter than hydrogen atom
(lightest known).
•
Cathode Ray tube animation
Proposed an atomic model known as the “plum pudding”
model (electrons = raisins in plum pudding; scattered
throughout) or chocolate chip ice cream.
4) Ernest Rutherford - 1911
• Performed the Gold Foil experiment, and
discovered positively charged nucleus with
positively charged particles called protons.
•
•
Gold foil experiment step by step
Gold Foil Experiment animation
• Proposed atomic model with massive (small but
heavy) nucleus with electrons in a circle around it
in a solar system model. Atoms are mostly empty
space.
Review 3 mins
• OQ: Describe 2 ways that John Dalton’s
work/theory was different from Democritus’s,
1 way it was similar.
OQ:
Rutherford discovered ________ly charged
protons located in the _________, whereas
Thomson discovered- _______ charged
________ located in a positive cloud.
1/21 p. 4 Atomic Theory Notes Cont’d
IQ: Which of the following apply to both JJ
Thomson and Rutherford’s atomic models? (More
than one answer possible)
a. Positive charge
b. Protons
c. Nucleus
d. Electrons
e. Mostly empty space
Review 3 mins
5) Niels Bohr - 1913
• Developed atomic model that placed
electrons in specific energy levels or orbits to
explain why they did not spiral toward & collide
with the nucleus.
• E-s can jump between levels by gaining (up) or
losing (down) energy as light, but can never be
found in between levels.
•
•
•
Model animation
Bohr model Youtube (start at 3:52)
Atomic models
6) James Chadwick - 1932
• Discovered neutron as a neutral particle in the
nucleus with the same mass as a proton (+).
• The discovery explained why the mass of an atom
could not be attributed entirely to the mass of
the p+s.
• Neutrons keep the protons/nucleus together with
a “strong force.”
•
Discovery of neutrons.
Nucleus
(protons &
neutrons)
(+) Positive Protons
(0) Neutral Neutrons
7) Erwin Schrodinger – 1926
• Described electrons as waves with their
probable location viewed as a cloud and
introduced a mathematical model of the
atom. Most current model, e-cloud or wave
mechanical model.Impossible to locate an e-’s
exact position. Youtube
•
Crash course (Acc)
e-
OQ
Whose model is represented above? Provide
evidence to support your answer.
a. Democritus
b. Dalton
c. JJ Thomson
d. Rutherford
1/22 Atomic Theory Timeline
• Answer IQ on green half sheet
• When finished, tape on p. 6
• Pink notes review sheet goes on p. 7
after you finish today.
• History of the Atomic Theory
• Brainpop
• Timeline
•
How Protons, electrons and neutrons were discovered (Youtube)
Highlights
1. Democritus
First - Atomos - Indivisible
2. John Dalton
Atomic Thoery - Add Together
3. J.J. Thomson
Electrons - “Plum Pudding”
4. Ernest Rutherford + Charged Nucleus - Gold Foil
5. Niels Bohr
Electrons Specific NRG Levels
6. James Chadwick
Neutrons (Jimmy Neutron)
7. Erwin Schrodinger
Electron Cloud Wave
Atoms
• Basic ________ of matter.
• The _________ particle of a
substance that has ____ of its
_____________.
• Called the ‘________ ______’ of
matter
• Example= the element Gold is
made of _______ atoms; all
exactly the _______, IF gold!!
1) Democritus - _________ BC
• ________ to develop the idea that _______ was
made of ___________ called atoms.
• Atoms in different materials were of different
__________________ which led to different
properties. Ex. Pepper atoms were spiky.
• The term “Atoms” comes from the Greek word
“atomos” which means “__________”
2) John Dalton - 1803
• Performed _______________ with different
substances.
i. Proposed atoms _________ in specific proportions
to make new stuff- _____________.
ii. An atom is indivisible, indestructible, tiny sphere
iii. Atoms of the same element are exactly _______.
iv. Determined that elements have ___________
atomic masses.
3) Joseph John Thomson - ________
• Discovered __________ through the use of a
cathode ray tube, proved that _______ were
further ___________.
• Mass of e-s 1800 times lighter than hydrogen
atom (lightest known).
Proposed an atomic model known as the “______
__________” model (electrons = raisins in plum
pudding; scattered throughout) or chocolate chip
ice cream.
4) Ernest Rutherford - 1911
• Performed the ________ ______
experiment, and discovered __________
charged ________ with positively charged
particles called _______.
• Proposed atomic model with massive (small
but ________ nucleus with electrons in a
circle around it in a solar system model.
Atoms are mostly empty _________.
Gold Foil Experiment
5) Niels Bohr - _________
• Developed atomic model that placed
________ in _________ energy _______or
orbits to explain why they did not spiral
toward & collide with the nucleus.
• E-s can ________ between levels by gaining
or losing _______ as light.
6) James Chadwick - 1932
• Discovered _________ as a neutral particle in
the nucleus with the same _________ as a
proton (+).
• The discovery explained why the mass of an
atom could not be attributed entirely to the
mass of the p+s.
• Neutrons keep the protons/______ together
with a “__________ force.”
(+) Positive Protons
(0) Neutral Neutrons
Nucleus
(protons &
neutrons)
7) Erwin Schrodinger – 1926
• Described _________as _________with
their probable location viewed as a _______.
Most current model, e-cloud or wave
mechanical model.
• _________to locate an e-’s exact _______.
e-
Highlights
1. Democritus
First - Atomos - Indivisible
2. John Dalton
Atomic Thoery - Add Together
3. J.J. Thomson
Electrons - “Plum Pudding”
4. Ernest Rutherford + Charged Nucleus - Gold Foil
5. Niels Bohr
Electrons Specific NRG Levels
6. James Chadwick
Neutrons (Jimmy Neutron)
7. Erwin Schrodinger
Electron Cloud Wave
1/26 Atomic Theory Rvw/Bill Nye
Atoms
IQ: Copy the following diagram and label the
atomic particles with the correct charges and
the scientist who discovered them:
OQ:
In order to jump farther away from
the nucleus, an electron will need to
a. lose energy
b. gain energy
c. gain more charge
d. lose some charge
1/30 Matterville Story
• IQ: Determine the atomic number of the
atom below. What is the electron in the
outermost level called and what would
happen if it leaves the atom?