Building Vocabulary Match each term with its definition by writing the letter of the correct definition on
the line beside the term in the left column.
5. nucleus
6. proton
7. neutron
=
c.
8. electron
9. atomic number
10. isotopes
11. mass number
12. energy level
a. the sum of protons and neutrons in the nucleus of an
atom
b. the very small center core of an atom
atoms of the same element that differ in the number
of neutrons, but have the same number of protons
d. the particle of an atom that moves rapidly in the
space outside the nucleus
e. a specific amount of energy related to the movement
of electrons in atoms
f. the particle of an atom with a positive charge
g. the number of protons in the nucleus of every atom
of an element
h. the particle of an atom that is neutral