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Review: Chemistry TEST 2: Primarily Chapter 3
Problems & Questions:
1 Who are the major historical figures central to discovering the existence and structure of the atom and
their major contributions?
Democritus- defined the word “atom”
Dalton- described that all matter was made of atoms and contributed Dalton’s Atomic Theory
JJ Thompson- discovered the electron (negatively charged) using the cathode ray tube.
Rutheford- discovered the nucleus is small, dense and positive in the Gold Foil Experiment. He also
determined that the nucleus is mostly empty space.
2 Draw a chart showing the charge, mass, location and symbol of protons, neutrons, and electrons
Subatomic Particle
Proton
Neutron
Electron
Charge
+1
0
-1
Location
Nucleus
Nucleus
Cloud orbitals
surrounding nucleus
3a Atomic Number =
proton #
3b Mass Number=
proton + neutron
4 Electron energy levels fill from inside
to
Mass
~1 amu
~1 amu
Negligible
0 amu
Symbol
p+
n0
e-
out
5 How many electrons can be on each electron energy level (Levels 1-6)?
Energy Level
# of Electrons
1
2
2
8
3
18
4
32
5
50
6
72
6 What cloud shape does s, p, d and f (no shape needed for f) orbital have and how many electrons fit
into each?
s- sphere (2)
p- peanut (6)
d-double peanut (10)
f- (14)
7 Explain what the strong force is and the purpose of it.
The strong force is the force that keeps the protons and neutrons in the nucleus. It holds them together
even though all of the protons are positively charged and should be repel.
8 What is an isotope?
Atoms of the same element that have different masses
9 What is an ion?
An ion is an atom or group of bonded atoms that have a positive or negative charge.
10 How are ions formed?
Losing or gaining electrons (remember that proton number will not change)
11 How can you find the following:
Atom
#p= atomic number
#n= mass (PT)- protons
#e= # p
Ion
#p= atomic number
#n=mass (PT)- protons
#e= proton - electron
Isotope
#p= atomic number
#n=isotope mass-protons
#e= # p
12 What are valence electrons?
Electrons that are found in the outermost energy level
13 Summarize what happens in a physical change, AND give an example of a physical change
In a physical change the substance’s identity is not changed. Examples: cutting, grinding, stretching,
melting, boiling, freezing, evaporation, etc.
14 Draw a box diagram showing a physical change.
15 Summarize what happens in a chemical change, AND give an example of a chemical change.
A substances identity is changed in a chemical change. Examples: rusting, combustion, tarnishing,
burning, etc.
16 Draw a box diagram showing a chemical change
17 Summarize what happens in a nuclear reaction, AND give an example of a nuclear reaction
The nucleus of an atom is changed. The numbers of protons are changed. Fusion and Fission are
examples
18 What is the mass defect? What is the mass converted into?
A small amount of mass is lost during fusion. The mass is converted into large amounts of energy.
19 Explain fission and fusion AND give an example of each. Which (fusion or fission) releases more
energy?
Fusion- combining of two smaller nuclei to produce 1 larger nucleus and lots of energy
Fission- splitting of a larger nucleus into 2 or smaller nuclei. Releases energy.
Fusion releases more energy than fission.
20 In Rutheford’s gold foil experiment, what 3 possible things happened to the particles when fired at the
gold foil? What conclusions can be determined from this?
Particles could have been shot through the atom (the atom is mostly empty space), deflected (the nucleus
is dense) or shot backwards (positive nucleus).
21 Draw a picture of Phosphorous, including p+, n0, and e- in the correct energy levels (be able to do
this for all elements 1-20 on the periodic table)
17 p+
17 n0
2e-
8e-
5e-
22 Write the 2 kinds of symbols (nuclear and hyphen notation) for an isotope of Calcium that has a mass
of 42.
20
Ca-42
Ca
42
23Compare and contrast ions, isotopes and atoms, as well as give examples.
Atoms- the mass number is the average atomic mass on PT and a neutral charge (Be, O, Na)
Ions- positive or negatively charged atom or groups of atoms (Ca2+, N3-)
Isotope- the number of neutrons is changed and the mass number is different from the average atomic
mass
24 Rubidium has two naturally occurring isotopes, Rb-85 (84.9118 amu) and Rb-87 (86.9092 amu). If
Rubidium has an average atomic mass of 85.47 amu, what is the abundance of each isotope (in percent)?
x(84.9118) + (1-x)(86.9092) = 85.47
84.9118x +86.9092 – 86.9092x = 85.47
-1.9974x = -1.4392
x= 0.72
Rb-85 = 72%
1-x = 0.28
Rb-87 = 28%
25 What is the average mass of Lithium if 7.42% exists as Li-6 (6.015 amu) and 92.58% exists at Li-7
(7.016 amu).
(.0742)(6.015) + (.9258)(7.016) = 6.9417258
26 What is the molar mass of the following:
Na
22.99amu
Zn 65.39 amu
CO2
44.01 amu
MgCl2 95.21amu
27 Determine the mass of the following:
2.0 moles AuCl
2.0 mol AuCl
3.1 moles BaF2
232.42 g AuCl = 460 g AuCl
3.1 mol
1 mole AuCl
175.35 g BaF2 = 543.59 g BaF2
1 mol BaF2
28 Determine the number of moles in the following:
4.1 x 103 atoms H20
72.3 g NaBr
72.3 g NaBr 1 mol NaBr
=0.703 mol NaBr
4.1 x 103 at H2O
102.89 g NaBr
29 Determine the number of atoms/molecules in the following:
4.7 moles FeCl2
4.7 mol FeCl2 6.022 x 1023 at FeCl2 = 2.8 x 1024 at FeCl2
1 mol FeCl2
1 mol H2O
6.022 x 1023 at H2O
= 6.8 x 10-22 at H2O
192.6 g BeO
192.6 g BeO 1 mol BeO
25.01 g BeO
6.022x 1023 at BeO = 4.637 x 10 24 at BeO
1 mol BeO