Name: ________________________________________________ Date: _________________________________ Period: _________
Unit 4 Quiz Study Guide – Atomic Theory, Ions & Isotopes
1. Review the rules for significant figures.
-
How many sig figs are in each of the following?
0.00098 - 2
-
300. - 3
8500 - 2
0.0070 - 2
30010 - 4
Solve the following problems and round to the correct number of sig figs.
80.2 - 93.40 + 803 = 789.9  790.
86.3 ÷ 4.2 = 20.54761905  21
2. Review dimensional analysis.
Convert 8300 ng to kg.
8300 ng 1 g
10-3 kg = 8.3 x 10-9 kg
9
10 ng
1g
Convert 1.2 miles to mm.
3. Atomic Theory
1. What is the difference between Democritus’ and Dalton’s Model of the Atom? Very similar – both thought
that atoms made up everything and were very small. Democritus named them, atomos, and Dalton said
they were indivisible.
2. How did Rutherford build on Thomson’s discovery? Describe each of their experiments and what the
outcomes were. Thomson used the cathode ray to determine that there was substructure to an atom
(positive + negative charge) and described it as “plum pudding.” Rutherford shot alpha particles (positive
charges) at a piece of gold foil and discovered the nucleus (where all the mass is contained) and that
electrons were around it outside (all the space).
3. Who is credited with discovering the nucleus? Why? Rutherford. When he shot the alpha particles at the
piece of foil they bounced back only in the center (the nucleus) where it was a dense concentration of
protons.
4. The Atom
-
-
What are the three subatomic particles and what are their charges?
Proton (+1), neutron (0 – neutral), electron (-1)
 Protons/Neutrons in the nucleus – all the mass
 Electrons orbit around – all the space
Complete the following table using your periodic table.
Number of
Neutrons
lead
Number of
Protons
82
Number of
Electrons
82
Atomic
Mass
207.2
Atomic
Number
82
Calcium
20
20
20
40.078
20
tantalum
73
108
73
180.95
73
radium
88
138
88
226
88
americium
95
148
95
243
95
lawrencium
103
159
103
262
103
Element
5. Ions
What is the difference between an ion and an atom? Ions are charged atoms (atoms with different number of
electrons – either gained or lost electrons).
Complete the following table using your periodic table.
Element
Name
Chlorine
silver
Oyxgen
Aluminum
Ion
Symbol
Atomic
Number
Mass
Number
# of
Protons
# of
Neutrons
# of
Electrons
Cl 
17
35
17
18
18
Ag+
47
107
47
60
46
O-2
8
16
8
8
10
Al 3+
13
27
13
14
10
6. Isotopes
What is the difference between an isotope and an atom? The isotope of an element is the element (neutral
atom) with a varied (different) mass. So same element, different mass. So same protons, different number of
neutrons – because protons + neutrons = mass.
Complete the following examples using your periodic table.
Isotope
Nuclear
Symbol
Atomic
Number
Mass
Number
# of
Protons
# of
Neutrons
# of
Electrons
calcium-40
40
Ca
20
20
40
20
20
20
Iron-56
56
Fe
26
26
56
26
30
26
Oxygen-18
18
O
8
8
18
8
10
8
79
197
79
118
79
Name
Gold-197
197
79
Au
REMINDER:
Hyphen Notation = element’s name – mass
Nuclear Symbol =
𝑚𝑎𝑠𝑠
Atomic Symbol
𝑎𝑡𝑜𝑚𝑖𝑐 #