Name: ________________________________________________
Midterm Review Packet- Answer Key
Date: _______________
1) 2. The atom is mostly empty space with a small, dense, positive nucleus. Most of the alpha particles in
Rutherford’s experiment passed through undeflected, but a small fraction of particles were deflected at an
angle or backwards when they came close to the nucleus because they have a positive charge and deflect
from the positive charge of the nucleus.
2) 1. The protons balance out the electrons in terms of charge.
3) 2. Electrons have more energy and are more unstable the farther they are from the nucleus. Electrons want
to be close to the nucleus because opposite charges attract.
4) 3. Good conductor of electricity is a metallic property. Nickel is the only solid metal. Iodine and sulfur are
solid nonmetals and mercury is a liquid metal.
5) 3. Metalloids have properties of both metals and nonmetals. They are located on the boron staircase. The 6
metalloids are: Boron, Silicon, Arsenic, Germanium, Tellurium, Antimony.
6) 4. Diamond and graphite have very different properties due to their different structural arrangements.
7) 3. Fluorine is the most electronegative element. The higher the electronegativity, the higher the tendency to
gain electrons.
8) 3. A chemical property is based upon changing the chemical structure or arrangement of the element. The
word react indicates a chemical reaction occurs which is classified as a chemical property. Malleable,
boiling point and conducting will not change the element, it is still magnesium.
9) 1. H2O Binary compound containing two types of elements chemically bonded.
10) 4. Ionic compounds must contain a metal and a nonmetal.
11) 2. Chlorine gains an electron when it becomes a Cl- ion. When an atom gains electrons, its radius increases.
12) 3. According to Reference Table H, ethanoic acid has a vapor pressure of 24 kPa, water= 39 kPa, ethanol=
86 kPa and propanone= 183 kPa.
13) 3. Nitrogen, Hydrogen and Oxygen are the three different elements in NH4NO3
14) 2. Ammonia gas is NH3(g). This is the gaseous form of a compound, which is a pure substance. Elements
and compounds are substances. HCl (aq) is HCl dissolved in water making it a mixture, air is a mixture and
salt water is a mixture.
15) 4. Temperature directly measures average kinetic energy. If you increase temperature, the average kinetic
energy increases which increases molecular motion. As the molecules move faster, they spread out which
causes the volume to increases. Temperature and Volume are directly related.
16) 1. B.A.R.F. Breaking=absorbs energy. Release energy= Forming. Cl2 is split up into two Cl molecules by
breaking its’ chemical bond.
17) 2. Table N states that 37K undergoes β+ decay which is a positron according to Table O.
18) 3. Gamma rays are pure energy which are only stopped by thick layers of lead or 12 feet of concrete.
Gamma rays are so powerful because they are very small and neutral with no charge.
19) 3. 9 protons= +9 charge in the nucleus. 10 electrons= -10 charge outside of the nucleus. Net charge= -10 +
9= -1 because there is one more electron than proton.
20) 1. Elements are placed in groups upon reactivity which relates to the number of valence electrons.
21) 1. Sodium has a larger radius because its 11 protons cannot pull in its 2 principle energy levels as strongly
as phosphorus which has 15 protons and a stronger pull on its 2 principle energy levels. Sodium is a metal
and phosphorus is a nonmetal.
Name: ________________________________________________
Midterm Review Packet- Answer Key
Date: _______________
22) 4. K= °C + 273
23) 2. Density can be used to identify a substance. D= mass/volume. The density of A and C are both 0.50 g/ml.
24) 4. Natural transmutation will always have one reactant and 2 or more products. This represents an unstable
nucleus naturally decaying. The other reactions show artificial transmutation by bombarding a nucleus with
another particle to force decay.
25) 3. Always round to the least number of significant figures when doing multiplication or division.
26) 3. Fusion combines light nuclei to form one heavier nucleus. Fission splits 1 large nucleus to produce
multiple smaller nuclei. Both release tremendous amounts of energy (atomic bomb, hydrogen bomb), fusion
is stronger than fission.
27) 4. k=kilo=103 therefore 50kJ is 50 x 103 J which equals 50,000 J which in scientific notation is 5 x 104 J
28) 3. 0.086 has 2 sig figs and 0.431 has 3 sig figs, leading zeroes are never significant. 3870 has 3 sig figs,
trailing zeroes without a decimal are never significant.
29) 1. Lead (II) = Pb+2 Chromate= CrO4-2. You need 1 of each ion to have a neutral compound.
30) 3. 16N has 7 protons and 9 neutrons, the ratio of protons to neutrons is not 1:1. All other atoms have a 1:1
proton to neutron ratio.
31) SKIP
32) 4. SO4-2 is the polyatomic ion present and called sulfate according to Table E.
33) 2. KNO3(aq) is aqueous. Anything aqueous has been dissolved in water and is classified as a homogeneous
mixture.
34) 4.
35) 3.
36) 4. S-2 has gained 2 valence electrons. This changes the S e-configuration from 2-8-6 to 2-8-8 as it forms S-2
37) 2. The energy to remove the most loosely bound electrons is the first ionization energy. Look up first
ionization energy values in Table S to see which element has the lowest. Sn= 709 kJ/mol, Sr= 549 kJ/mol,
Be= 900 kJ/mol, Br= 1140. kJ/mol.
38) SKIP
39) 2. Melting is a phase change at constant temperature. Q=mHf= (5.00 g)(334 J/g)= 1670 J
40) 4. Pressure and volume are indirect. As you increase volume (space between gas particles and the container
walls) this decreases the number of gas particle collisions which causes pressure to decrease.
41) 2-7-3
Aluminum-27 has 13 electrons. It’s ground state configuration is 2-8-3 according to the Periodic Table. A
possible excited state configuration is 2-7-4. The electrons are not as close to the nucleus as possible,
making it excited. The configuration still represents aluminum because it has 13 electrons.
42) 15 neutrons
Si-29 is an atom of silicon with a mass number of 29. Silicon has 14 protons and if mass= protons +
neutrons then to solve for the number of neutrons use the following: 29= 14 + neutrons. Neutrons= 2914=15.
Name: ________________________________________________
Midterm Review Packet- Answer Key
Date: _______________
43) Atomic mass= ( .9222 x 27.98) + ( .0469 x 28.98) + ( .0309 x 29.97)
= (decimal abundance x atomic mass of) + (decimal abundance x atomic mass of ) …
of isotope 1
isotope 1
of isotope 2
isotope 2
Atomic
Mass
44) % error = measured value – accepted value
accepted value
x
100
% error= 3.29 – 3.09 x 100
3.09
% error= 6.47 %
45) 120 °C The graph shows the second phase change (flat line) occurs at 120 °C. This is the vaporization point
for the sample.
46)
The sample is in the solid phase during the first minute of heating. This phase and time exists before the
samples melting point.
47) 3 minutes. The sample is a liquid from 4 minutes after melting has finished until 7 minutes, when
vaporization begins.
48) 30 kJ
The reading passage indicates the sample is absorbing energy at a rate of 15 kJ per minute. It takes the
sample 2 minutes to melt therefore 2 min x 15 kJ/ min = 30 kJ
49)
Uut
Uut is in Group 113 and has 3 valence electrons therefore its dot diagram will have 3 electrons draw around
it’s atomic symbol.
50) +113
The atomic number is 113 therefore the element has 113 protons giving the nucleus a charge of +113.
Name: ________________________________________________
Midterm Review Packet- Answer Key
Date: _______________
51) In, Tl, Ga, Al, or B.
Any element in group 13 will be chemically similar to Uut because it is in Group 13. This means that it
forms the same type of ions as other group 13 elements because they have the same number of valence
electrons.
52) 3 significant figures.
The calculated mass of CuSO4•H2O is 2.13 g according to the data table.
53) % composition by mass=
mass of the part
mass of the whole
x
100

% mass= 0.76
2.13
x
100
mass of part= mass of water= 0.76 g
mass of whole= mass of the hydrate= 2.13 g
54) To ensure that all of the water in the hydrate has evaporated.
55) To decay to 1/16 its original size it underwent 4 decays (see table). The time it takes for 1 decay is the halflife, which according to Reference Table N is 5715 years for C-14. Therefore 4 x 5715 years= 22860 years.
Amount
# of decays
1
0
1/2
1
1/4
2
1/8
3
1/16
4
56)
14
C
6
0
-1
e +
14
N
7
57) The sodium ion transferred an electron to the chloride ion to form Na+ and Cl-. An ionic bond forms
between two ions which form after a transfer of electrons.
58) SKIP
59) SKIP