8.    An atom has an atomic number of seven.   How many electrons are in its outer shell?
        a.  2         b.  5         c.  7         d.  14

An atom with an atomic number of 7 has 7 protons.  This means it also has 7 electrons.  The first electron shell or energy level can accommodate only 2 electrons.  That leaves 5 electrons for the second energy level.

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Emma Erdahl, Associate Professor of Biology
Northern Virginia Community College
Revised 8/23/00