Study Buddy: Atomic Structure and Nuclear Chemistry
Development of the Modern Atomic Theory
Scientist
Experiment
No experiment
Democritus
Use
experiments of
previous
scientists
Dalton
Cathode ray
Thomson
Gold foil
Rutherford
Alpha particles
Chadwick
Uses findings
from previous
scientists and
Quantum
theory
Multiple
experiments
Bohr
Modern
Atom
Findings
Atoms are the
smallest form of
matter and cannot be
created, destroyed or
divided
Postulates: Atoms of
elements are identical;
atoms can’t be created
or destroyed; atoms
combine in whole
number ratios in a
chemical reaction
Discovered the
electron “Plumpudding” Model
Limitations
Did not explain
chemical behavior
Did not include subatomic particles
Did not explain
deflection pattern of
alpha particles as
seen by Rutherford
Could not explain
why electrons do
not crash into the
nucleus
No modification of
atom model
Discovered the proton
and nucleus. Atoms
contain mostly empty
space.
Discovered the
neutron
Electrons are in orbits
of differing energy
levels.
Does not explain the
behavior of other
elements just
hydrogen
Electron cloud and
dual nature of
electrons
Still doesn’t explain
the exceptions
Location
Nucleus
Nucleus
outside the nucleus
Charge
1+
0
1-
14
6
11/3/14
C
Electron
cloud
Mass
1
1
0 or 1/1840
Nuclear Symbol
Carbon-14
Protons:
Neutrons:
Atomic Number:
Mass Number:
No new
model/neutron later
add to nucleus
Identify the proton, electron, neutron
in the model below.
Parts of an Atom (8th Grade Review)
Sub-atomic Particle
Proton (p+)
Neutron (n°)
Electron (e-)
Model
____6____
____8____
____6____
____14___
SCIE_CHEM_ATOMIC_MAT_STUDYBUDDYTE_AL
electron
+
+
neutron
proton
What is the atomic number of the
above models? 2
What is the atomic mass? 4.00 amu
What element is this? Helium
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1
Complete the Venn diagram below stating similarities and differences in the numbers of the
subatomic particles for the same element.
#p≠#e
Same #
proton
and
neutron
Cation (+)
Anion (-)
Magnesium-25
25
12𝑀𝑔
Magnesium-24
24
12𝑀𝑔
Magnesium ion
24
2+
12𝑀𝑔
#p=#e
Same #
proton
and
electrons
No charge
Different # of neutrons
Types of Nuclear Radiation
Type
Composition
Two protons and
two neutrons
High energy
electron
Alpha
Beta
Gamma
Energy
Reaction Type
Fission
Fusion
Symbol
4
α or 2𝐻𝑒
β or
0
−1𝑒
0
0𝛾
Penetration/Energy
Reaction Example
Blocked by paper, low
energy
Blocked by wood, medium
energy
Blocked by lead or
concrete, high energy
Definition
149
62𝑆𝑚
→
145
60𝑁𝑑
165
61𝑃𝑚
→
0
−1𝑒
9
4𝐵𝑒
+ 42𝐻𝑒
+ 165
62𝑆𝑚
→ 49𝐵𝑒 + 00𝛾
Diagram
Uses
Splitting of a nucleus into smaller
fragments
Fuel for nuclear power
plants
Combining nuclei to produce a
nucleus of greater mass
Energy source for
nuclear bombs
Reaction that occurs in
the sun
Balance the following nuclear equations:
58
0
58
228
224
4
28𝑁𝑖 → −1𝑒 + 29𝐶𝑢
88𝑅𝑎 → 86𝑅𝑛 + 2𝐻𝑒
12
6𝐶
→ 00𝛾 + 126𝐶
Element X has two common isotopes, 79X (50.7%) and 81X (49.3%). What is the average atomic
mass of element X? Identify element X.
Average atomic mass = (79)(0.507) + (81)(0.493) = 79.9 amu = Bromine (Br)
Copper occurs naturally as Copper-63 and Copper-65. Which Based on the atomic mass on the
periodic table, which isotope is more abundant?
The average atomic mass of copper is 63.546 amu. Since the average is closer to Copper63, it can be assumed that Copper-63 is more abundant.
Why can chemists not simply round off atomic mass to the nearest whole number and say that
would be the mass of the most abundant isotope?
If copper (63.546 amu) were rounded, the result would be copper-64, which does not exist.
11/3/14
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