ISOTOPES
Name:________________________ Period:________
1. Write the isotopic symbols for the isotopes of uranium having the following number of neutrons.
a.
142 neutrons
b.
143 neutrons
c.
146 neutrons
2. Fill in the following table:
Name
# of protons
# of neutrons
# of electrons
Boron-10
Sulfur-33
Iodine-127
Chlorine-36
Calcium-40
Tin-119
3. Fill in the following table:
Name
# of electrons
# of protons
carbon-14
carbon-
# of neutrons
atomic #
mass number
50
119
8
6
tin-120
3
4
sodium-
23
4. What do isotopes of the same element have in common? How do isotopes of the same element differ?
5. Write the isotopic symbols for argon-36, argon-38, and argon-40.
6. Distinguish among mass #, atomic mass, atomic # and atomic mass unit.
7. How is the carbon-12 atom used to define atomic mass unit?
8. Why is the atomic mass of nitrogen 14.0067 and not 14?
9. Element X has two naturally occurring isotopes. The isotope with mass number 10.0 amu has a relative
abundance of 20.0%. The isotope with a mass number of 11.0 amu has a relative abundance of 80.0%.
Calculate the value of the atomic mass of element X. State the atomic number and true identity of
element X.
10. The lithium found in a hearing aid battery has two naturally occurring isotopes. Lithium-6 has a mass of
6.015121 amu and an abundance of 7.42%. Lithium-7 has a mass of 7.016003 amu and an abundance of
92.58%. Calculate the atomic mass of lithium.
11. Silver found in jewelry has two naturally occurring isotopes. Silver-107 has a mass of 106.905092 amu
and an abundance of 51.35%. Silver-109 has a mass of 108.904757 amu and an abundance of 48.65%.
Calculate the atomic mass of silver.
12. Carbon is used to date objects that used to be living material. A certain percentage of carbon-14 exists
in the air due to sun radiation creating C-14. Once C-14 is made, it decays into carbon-12. Scientists
can look at the % of C-14 compared to C-12 to find out how old something is when it died since when it
dies, it stops consuming Carbon dioxide through photosynthesis. Draw Bohr models of C-12 and C-14.
They compare them using the following words in your comparison: Atomic mass, mass number,
atomic number, protons, neutrons, electrons, isotope.