1) The nucleus of an atom contains protons and ____. 2) Electrons ____ the nucleus in fixed energy levels. 3) Metals are found on the ____ side of the metalloid staircase. 4) Nonmetals are found on the ____ side of the metalloid staircase, except for the element ____, which is found in Group 1. 5) A group is a ____ (up and down), and a period is a ____ (across). 6) The Atomic Number of an element is the number of ____ found in every atom of that element. Therefore, the atomic number, or the number of protons, determines the ____ of an element. 7) The ____ is the average mass of one atom of an element. 8) ____ = number of protons = number of electrons 9) Mass number = ____ 10) # of neutrons = ____ 11) ____ shows the number of electrons in each energy level. 12) The period number is equal to the number of ____ an element has. 13) Valence electrons are the ____ electrons in an atom and occupy the ____ energy level. 14) Valence electrons are responsible for chemical reactions and the formation of ____. 15) The group number often determines the number of ____.

Periodic Table Review

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