4. A hydrogen atom is made up of one proton and one electron. The proton and electron stay near each other because a) Positive and negative charges repel
b) Positive and positive charges repel
c) Positive and negative charges attract
d) Two negatives make a positive

5. The atomic number of an atom is
a) The mass of the atom
b) The number of protons added to the number of neutrons
c) The number of protons
d) Negatively charged

6. The atoms of the same element can have different isotopes. An isotope of an atom
a) Is an atom with a different number of protons
b) Is an atom with a different number of neutrons
c) Is an atom with a different number of electrons
d) Has a different atomic number

7. The atomic mass of an element is
a) The average mass of all the isotopes of the element
b) A measure of the density of that element
c) The mass of the most common isotope of that element
d) The number of protons and electrons in the atoms of the element

8. An element and an atom are different but related because
a) A particular element is made up of many different types of atoms
b) A molecule is the same as an atom
c) An element is made up of all the same type of atom
d) An element is smaller than an atom

9. The periodic table shows that a carbon atom has six protons. This means that a carbon atom also has
a) Six electrons
b) Six neutrons
c) More protons than electrons
d) An atomic mass that equals six

10. The atomic number of nitrogen is 7. The atomic mass is 14.01. This means that
a) All nitrogen atoms have exactly 7 neutrons.
b) A small percentage of nitrogen atoms have fewer than 7 neutrons
c) A small percentage of nitrogen atoms have more than 7 neutrons
d) Some nitrogen atoms have fewer than 7 electrons

11. Using the following data, calculate the average atomic mass of magnesium (give your answer to the nearest .01 u) : Show all work!

Isotope: 24
Mg Percent abundance: 78.70%
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Isotope: 25
Mg Percent abundance: 10.13%
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Isotope: 26
Mg Percent abundance: 11.17%
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