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*Round to 3 decimal places AND show your work!
Atomic Mass Worksheet
1. How do isotopes of an element differ? How are they similar?
2. How many electrons, protons, and neutrons are in each of the following?
Electrons
Protons
a. Gallium-64
Neutrons
b. Fluorine-23
c. 48Ti
d. 8He
3. Boron has two naturally occurring isotopes: boron-10 (abundance = 19.8%, mass= 10.013), and boron11 (abundance = 80.2%, mass = 11.009 amu). Calculate the atomic mass of boron.
4. An isotope of mercury has 80 protons and 120 neutrons. What is the mass number of this isotope?
5. How many protons and electrons are contained in an atom of the element Antimony?
Protons:__________________ Electrons: _________________
6. What is the mass number of potassium-39?
7. Is the charge of a nucleus positive, negative, or zero?
8. The volume of an atom is made up of mostly _____________________ .
9. The mass of an atom is located in the ____________________________.
10. Silver has two naturally occurring isotopes. Ag-107 has an abundance of 51.82% and a mass of 106.9
amu. Ag-109 has a relative abundance of 48.18% and a mass of 108.9 amu. Calculate the atomic mass
of silver.
11. Magnesium consists of three isotopes with masses of 23.98 (78.6%), 24.98 (10.1%), and 25.98 (11.3%).
Calculate the atomic mass of Mg.
12. What is the atomic mass of silicon if 92.21% of its atoms have a mass of 27.977 amu; 4.70% have a
mass of 28.976 amu, and 3.09% have a mass of 29.974 amu?
13. Calculate the atomic mass of titanium. The five titanium isotopes have atomic masses and relative
abundances of 45.953 amu (8.00%), 46.952 amu (7.30%), 47.948 amu (73.80%), 48.948 amu (5.50%),
and 49.945 amu (5.40%).
14. Chromium has 4 naturally occurring isotopes: Cr-50 (4.35%, 49.946 amu), Cr-52 (83.79%, 51.941 amu),
Cr-53 (9.50%, 52.941 amu), Cr-54 (2.36%, 53.939 amu). Calculate chromium’s atomic mass.
15. Nitrogen has two naturally occurring isotopes, 14N and 15N. The atomic mass of nitrogen is 14.007
amu. Which isotope is more abundant in nature? Explain.