PISD Chemistry December Benchmark Final Exam Review 2015 KEY
1 Describe the differences between solids, liquids, and gases. Draw a diagram of atoms in the solid state
changing to liquid state changing to gaseous state.
Solids have tightly packed particles, with high density. They have a definite volume and shape.
Liquids have particles that move past each other. Their density is lower than solids. They have definite
volume but take the shape of their container.
Gases have particles that are very far apart from each other. They have a density about 1000 times less
than a solid. They take the volume and shape of whatever container they are put in.
2 Explain the difference between an extensive property and an intensive property. Give 4 examples of each.
Extensive properties depend on the amount of matter that you have: mass, volume, length, amount of
energy.
Intensive properties do not depend on the amount of matter present: density, boiling point, melting
point, ability to conduct heat/electricity.
3 Explain the difference between a physical change and a chemical change. Give 4 examples of each.
Physical changes do not change the identity of the substance: cutting paper, dissolving a solid in water,
boiling, freezing.
Chemical changes result in a new substance being formed: burning charcoal, digesting food,
photosynthesis, forming water from hydrogen and oxygen.
4 Explain the difference between a mixture and a pure substance. Give 4 examples of each.
A mixture is a blend of substances that can be physically separated: oil and water; salt and sand; blood;
milk.
A substance is a form of matter that cannot be broken down without a chemical reaction—it is either an
element or a compound: CO2, H2O, copper, gold
5 Explain what apparatus and procedure you would use to separate a mixture of sand, salt, water, and iron
shavings.
First, use a magnet to separate the iron from the mixture. Then add the sand and salt mixture to water
to dissolve the salt. Pour the mixture through a filter to separate out the sand. Boil the saltwater
solution to remove the water and remain with salt.
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
6 For each scientist in the table below, discuss their experiment, including special equipment, their key
conclusion, and how it changed our view of the atom:
Scientist
Experiment/Key Equipment
Key Conclusions
Thomson
Cathode ray tube: every gas
had a bright stream of light,
which was attracted to a
positive plate, cast a shadow,
and moved a pinwheel
Every element contains
negative particles—
electrons, which have
mass
Rutherford
Gold Foil Experiment: alpha
particles were shot at gold
foil. Most passed straight
through, but some were
deflected back at high angles
Dalton’s Atomic Theory:
-All matter is composed of
atoms
-Atoms are indivisible and
indestructible
-All atoms of the same
element are identical in mass
and properties
-Compounds are formed by a
combination of two or more
different kinds of atoms
-A chemical reaction is a
rearrangement of atoms
Atoms have a small,
dense, positive nucleus
surrounded by mostly
empty space
Bohr Atomic Model:
-The atoms has a small,
positively charged nucleus
surrounded by electrons that
travel in circular orbits, similar
to the planets in the solar
system
-Sometimes called the Shell
Model of the Atom
-Gives quantized energy
levels for the orbit of
electrons, which
explains why the
electrons do not fall into
the nucleus
-Explains the behavior or
electron energy level
transitions for a
hydrogen atom model
Dalton
Bohr
-First evidence-based
explanation of the atom
-Gave a definition of a
compound and of
chemical reactions
How did it change our
view of the atom?
Atoms have smaller
particles in them; if
every element contains
negative particles, it
must also contain
positive charge
All of the positive
charge in an atom is
centered in a tiny
fraction of the atom’s
volume
-Atoms are indivisible
because there are
protons, neutrons, and
electrons
-All atoms of the same
element are not
identical in mass
because of isotopes
-Simplistic in its
treatment of the
electron path as a
simple circle, instead of
a 3D shape
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
Isotope
Cu-63
Cu-65
Relative
Abundance
69.17 %
30.83 %
Mass (amu)
62.929
64.927
7 Using the table above, find the atomic mass of the element.
Average atomic mass = (.6917 x 62.929) + (.3083 x 64.927) = 63.54 amu
8 Solve the following mole calculations:
a. How many grams are in 4.23 moles of calcium?
40.078 𝑔
4.23 mol Ca x 𝑚𝑜𝑙 𝐶𝑎 = 170 g Ca
b. How many moles are in 56.98 grams aluminum?
1 𝑚𝑜𝑙 𝐴𝑙
56.98 Al x 26.98 𝑔 𝐴𝑙 = 2.112 mol Al
c. How many atoms are in 13.5 grams of zinc?
1 𝑚𝑜𝑙
6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠
13.5 g Zn x
x
= 1.24 x 1023 atoms Zn
65.39 𝑚𝑜𝑙
𝑚𝑜𝑙
d. How many moles are in 3.450 x1023 atoms of lead?
1 𝑚𝑜𝑙𝑒 𝑃𝑏
3.450 x1023 atoms of Pb 6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 𝑃𝑏
= 0 .5731 mol Pb
23
e. How many moles are in 2.45 x 10 atoms of magnesium?
1 𝑚𝑜𝑙𝑒 𝑀𝑔
2.45 x 1023 atoms Mg x 6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 𝑀𝑔 =
f. How many grams are in 7.651x1024 atoms of silver?
1 𝑚𝑜𝑙 𝐴𝑔
107.868 𝑔 𝐴𝑔
7.651 x 1021 atoms Ag x 6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 𝐴𝑔 x 1 𝑚𝑜𝑙 𝐴𝑔 =
9 Perform the following calculations
a. Find the density of a rectangular piece of metal with mass of 48.5 g and the dimensions 2.0cm by 3.0cm by
𝑚
48.5𝑔
7.0cm. d = = (2𝑥3𝑥7)=42
= 1.2 g/cm3
𝑣
𝑐𝑚3
b. Find the volume of a substance with density of 1.79 g/mL and mass of 34.5 g.
𝑚
34.5𝑔
v = 𝑑 = 1.79 𝑔/𝑚𝐿 = 19.3 mL
c. Find the mass of a coin with volume of .75 cm3 and density of 2.73 g/cm3.
m = d·v = (.75 cm3)(2.73 g/cm3) = 2.05 g
d. A measured mass of an unreactive metal was dropped into a graduated cylinder half filled with water. The
following measurements were made. What is the density of the metal?
Mass of metal
27.275 g
Volume of water before addition of metal
11.4 mL
Volume of water after addition of meatal
15.8mL
d=
𝑚
𝑣
27.275 𝑔
= (15.8−11.4)=4.4 𝑚𝐿 = 6.2 g/mL
e. 12.5 m to cm
12.5 m x
102 𝑐𝑚
1𝑚
=1250 cm
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
f. 8.7 g to kg
1𝑘𝑔
8.7 g x 102 𝑔 =0.0087 kg
g. 42.0 mL to nL =4.2 x 107 nL
42.0 mL x
1𝐿
103 𝑚𝐿
x
109 𝑛𝐿
1𝐿
=4.20 x 107 nL
h. Convert 5.32 kg to µg
5.32 kg x
103 𝑔
1𝐾𝑔
X
106 𝜇𝑔
1𝑔
=
10 Determine the number of significant figures in the following measurements
a. 20.00 ____4_____
c. 40.080 ___5_____
b. 184,345 __6______
d. 4,000,000 ___1____
11 Define the mole
a. How many atoms are in 1 mole of zinc? 6.02 x 1023 atoms of Zn
b. How many grams are in 1 mole of zinc? 65.38 g/mole of Zn
12 Sketch out the electromagnetic spectrum. Include: x-rays, microwaves, gamma rays, UV light, IR light, visible
light, and radio waves.
a. Show how the frequency of electromagnetic radiation goes from low to high across the spectrum.
b. Show how the wavelength of electromagnetic radiation goes from long to short across the spectrum.
c. Show how the energy of electromagnetic radiation goes from low to high across the spectrum.
high frequency
low frequency
short wavelength
long wavelength
high energy
low energy
gamma rays  X rays  UV visible light  IR  microwaves, radar  radio, TV
13 Sketch out the visible light spectrum. Label the colors.
a. Show how the frequency of electromagnetic radiation goes from low to high across the spectrum.
b. Label 400nm and 700nm.
c. Show how the energy of electromagnetic radiation goes from low to high across the spectrum.
high frequency
low frequency
400 nm wavelength
V
I B G Y O R
700 nm wavelength
high energy
low energy
14 Perform the following calculations:
a. What is the frequency of electromagnetic radiation with a wavelength of 1.5 x 10-3 m?
3.00 x 108 m/sec
frequency = speed of lightwavelength = 1.5 𝑥 10−3 𝑚 = 2.0 x 1011 Hz
b. What is the wavelength of electromagnetic radiation with a frequency of 2.8 x 1015 Hz?
wavelength = speed of lightfrequency =
3.00 x 108 m/sec
2.8 𝑥 1015 𝐻𝑧
= 1.1 x 10-7 m
c. What is the energy of electromagnetic radiation with a frequency of 5.9 x 1016 Hz?
energy = Planck's constant x frequency = (6.63 x 10-34 Js)(5.9 x 1016 Hz) = 3.91 x 10-17 J
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
15 Write the electron configuration and noble gas configuration for the following elements:
a. Phosphorus (atomic #15) 1s22s22p63s23p3
b. Palladium (atomic #46) 1s22s22p63s23p64s23d104p65s23d8
c. Potassium (atomic #19) 1s22s22p63s23p64s1
16 For each of the following groups, what ending electron configuration do the elements have?
a. Group 1 and 2 elements
Group 1: s1 Group 2: s2
b. Group 13 to 18 elements
all end with p, from p1 (group 13) to p6 (group 18)
c. transition metals
all end with d, from d1 to d10
d. inner transition metals
all end with f, from f1 to f14
17 Explain the contributions of Mendeleev and Mosely to the modern periodic table arrangement.
Dmitri Mendeleev gets credit as "Father of the Periodic Table." He arranged the elements by mass and
reactivity, leaving blank spaces for those he thought were still undiscovered. Moseley later rearranged
the table by atomic number.
18 For each of the following families on the periodic table, list how many valence electrons they have and what
you know of their properties:
Alkali metal
1 valence electron
Form ions with +1 charge
Fairly reactive as group
Alkali earth metals
2 valence electrons
Form ions with +2 charge
Halogens
7 valence electrons
Flourine is most
electronegative element
Form ions with -1 charge
Found as diatomic
elements in nature (F2,
Br2, Cl2, I2)
Noble gases
8 valence electrons
(except He which has 2)
Unreactive
Do not form compounds
19 Explain the group and period trends on the periodic table for the following
a. atomic radius:
group trend--radius increases, because additional energy levels are further from the nucleus
periodic trend--radius decreases, because electrons are added at the same energy level and are
increasingly attracted to the larger nucleus
b. ionization energy:
group trend--energy decreases, because it is easier to remove electrons that are further from the
nucleus
periodic trend--increases, because it is more difficult to remove the electrons as they are increasingly
attracted to the larger nucleus
c. electronegativity:
group trend--in general, decreases down a group
periodic trend--in general, increases across a period
Highest electronegativity: fluorine
Lowest electronegativity: cesium.
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
20 Fill out the table below for the different types of bonds:
Types of elements
involved with this type of
bonding
What holds the atoms
together?
What properties do these
types of compounds
have?
Ionic
metal + nonmetal
Covalent
two or more nonmetals
ionic forces of attraction between
oppositely charged ions
sharing of electrons between two atoms
crystalline solids
brittle
high melting points
electrolytes
called "salts"
can have many physical forms
low melting points
non-electrolytes
21 Explain how electrons move in a metallic bond and why they are considered good conductors of heat and
electricity, malleable, and ductile.
Metal atoms pack closely together and their outer orbitals overlap. This allows the valence electrons to
move freely throughout the lattice. These are known as delocalized electrons. The attraction between the
metal cations and the surrounding sea of valence electrons is known as metallic bonding.
The free movement of the valence electrons is what allows for electrical conductivity--the electrons move
towards a positive charge, and this movement is a current. Because there are no repulsive forces within a
metal lattice, any force on the lattice causes its structure to rearrange, rather than break, which accounts for
the malleability and ductility of metals.
22 Draw the Lewis dot structure for the following ionic compounds
a. K3P
b. CaCl2
Note: Students should be able to
represent dot structures for ionic
compounds in either convention.
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
23 Draw the Lewis dot structure for the following compounds and identify the molecular and electron pair
geometries of each
a. CH4 Tetrahedral
H
C
H
b.
H
H
H2O
tetrahedral- bent
O
H
PF3
Tetrahdral- trigonal pyramidal
:
c.
H
P
H
H
d. CO2
H
linear
O=C=O
e.
BH3 Trigonal planar
H
B
H
H
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PISD Chemistry December Benchmark Final Exam Review 2015 KEY
24 Write the chemical formula for each of the following:
a. lead (II) oxide
PbO
b. lead (IV) sulfide
PbS2
c. barium nitrate
Ba(NO3)2
d. aluminum hydroxide
Al(OH)3
e. zinc chloride
ZnCl2
f. copper (II) oxide
CuO
g. potassium sulfate
K2SO4
h. potassium oxide
K2O
i. cobalt (III) fluoride
CoF3
j. copper(II) sulfate pentahydrate CuSO4 ·5H2O
k. phosphoric acid
H3PO4
l. sulfurous acid
H2SO3
25 Name the following compounds:
a. PBr5
b. PbI4
c. N2O3
d. SO3
e. Ag3PO4
f. CaO
g. Cu(OH)2
h. CoCl2·6H2O
i. HCl
j. NH4Br
phosphorous pentabromide
lead (IV) iodide
dinitrogen trioxide
sulfur trioxide
silver phosphate
calcium oxide
copper (II) hydroxide
cobalt(II) chloride hexahydrate
hydrochloric acid
ammonium bromide
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