Honors Chemistry- Chapters 3 and 21 Homework Packet
The Atom/Nuclear Chemistry
1) Complete the following table on the subatomic particles.
Particle
Location in Atom
Relative Mass
Proton
Electron
Neutron
2) What is that atomic number of an element?
3) (a) What are isotopes?
(b) How are isotopes of a particular element alike?
(c) How are they different?
4) What is the mass number of an isotope?
Relative Charge
5) Complete the following table.
Symbol
# of protons
# of neutrons
# of electrons
Net charge
20
20
23
28
20
35
44
36
15
16
-3
78
120
0
238U
0
(hyphen notation)
(nuclear notation)
Aluminum-27
(nuclear notation)
(nuclear notation)
(hyphen notation)
6) What is the average atomic mass of an element?
7) Three isotopes of argon occur in nature: Argon-36 (0.337%), Argon-38 (0.063%),
and Argon-40 (99.6%). Calculate the average atomic mass of argon based on
these data.
8) Naturally-occurring boron has two isotopes: Boron-11 (80.2%) and Boron-X
(19.8%). The average atomic mass of boron is 10.81 amu. What is the mass
number of the second isotope of boron given these data?
9) (a) What is the molar mass of an element?
(b) What two quantities does molar mass relate?
10) (a) How many atoms are in 1 mole of an element?
(b) What name is given to this number?
11) To two decimal places, write the molar mass (with units) of the following elements:
(a) Iron
(c) copper
(b) Neon
(d) bromine
12) Determine the mass (in grams) of each of the following. Show your work and
report your answers to the correct number of significant figures.
(a) 0.0384 mol K
(b) 6.755 mol Pb
13) Determine the number of atoms in each of the following. Show your work and
report your answers to the correct number of significant figures.
(a) 0.250 mol S
(b) 1.50 mol Na
14) Determine the mass (in grams) of each of the following. Show your work and
report your answers to the correct number of significant figures.
(a) 25 atoms W
(b) 4.50 X 1012 atoms Cl
15) Determine the number of moles in each of the following. Show your work and
report your answers to the correct number of significant figures.
(a) 8.24 X 109 grams P
(b) 0.0355 grams I
16) Determine the number of atoms in each of the following. Show your work and
report your answers to the correct number of significant figures.
(a) 0.02550 grams Pt
(b) 7.02 grams Si
17) Why do some nuclei undergo radioactive decay yet others do not?
18) What changes in atomic number AND mass number occur in each of the following
types of radioactive decay?
Change in atomic
number
Change in mass
number
Alpha Decay
Beta Decay
Positron Emission
Gamma Decay
19) Complete the following nuclear decay equations AND identify the type of decay.
(a)
(b)
(c)
(d)
20) The 238Pu isotope undergoes alpha decay. Write the balanced, nuclear decay
equation showing the parent nucleus, the daughter nucleus, and the emitted
particle.
21) The 75As daughter nucleus was produced from beta decay. What is the identity of
the parent nucleus? Write the balanced nuclear decay equation.
22) The 207Bi isotope undergoes positron emission. Write the balanced, nuclear decay
equation showing the parent nucleus, the daughter nucleus, and the emitted
particle.
23) Distinguish between nuclear fusion and nuclear fission. Give an example of where
each process is found.