Multiple Choice
In a simplified model of atomic structure, how an atom reacts chemically depends primarily on which of the following?
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9. Electrons in Atoms and the Periodic Table
Valence Electrons of Elements (Simplified)
Multiple Choice
For a main-group element, what is the simplest way to determine how many valence electrons it has using the periodic table?
A
Use the element’s group (column) number: the group number equals the number of valence electrons for main-group elements (e.g., Group 17 has 7).
B
Count the total number of electrons in the atom: the total number of electrons always equals the number of valence electrons.
C
Use the element’s atomic number: the atomic number equals the number of valence electrons.
D
Use the element’s period (row) number: the period number equals the number of valence electrons.
Verified step by step guidance1
Understand that main-group elements are those found in the s- and p-blocks of the periodic table, which include groups 1, 2, and 13 through 18.
Recall that valence electrons are the electrons in the outermost shell of an atom and are important for chemical bonding and reactivity.
Note that for main-group elements, the group number (the column number) corresponds directly to the number of valence electrons. For example, elements in Group 1 have 1 valence electron, Group 2 have 2, and Groups 13 to 18 have 3 to 8 valence electrons respectively.
Recognize that the atomic number represents the total number of electrons in a neutral atom, not just the valence electrons, so it is not the simplest way to find valence electrons.
Understand that the period number indicates the energy level of the valence electrons but does not tell you how many valence electrons there are.
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