Download Protons, Neutrons, and Electrons—How Atoms Differ

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LESSON 2
Protons, Neutrons, and Electrons—How Atoms Differ
Directions: On each line, write the term from the word bank that correctly replaces the underlined words in each
sentence. NOTE: You may need to change the form of a term.
atomic number
average atomic mass
ion
isotope
mass number
nuclear decay
radioactive
spontaneous
1. Carbon-12, carbon-13, and carbon-14 are examples of atoms of the same element that
have different numbers of neutrons.
2. Radioactive elements emit radiation without external force or cause.
3. Nitrogen’s number of protons is seven.
4. A radioactive element goes through a process in which its unstable atomic nucleus
changes into another more stable nucleus by emitting radiation.
the average mass of the element’s isotopes, weighted according to the abundance of
each isotope for the element.
6. Na+ and F– are examples of atoms that are no longer neutral because they have gained
or lost electrons.
7. Uranium is an example of an element that is able to spontaneously emit radiation.
8. Carbon-12 is the most abundant isotope of the element; it has a sum of protons and
neutrons equal to 12.
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Understanding the Atom
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5. Beneath each element’s symbol on the periodic table, there is a number that provides