Multiple Choice
Which of the following compounds has a total of 10 valence electrons?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following best describes how to use the periodic table to determine the number of valence electrons for a main-group element?
A
All elements in the same period have the same number of valence electrons.
B
The period number indicates the number of valence electrons for all elements.
C
Count the number of electrons in the outermost shell, which corresponds to the group number for groups 1, 2, and 13–18.
D
Subtract the atomic number from the mass number to find the number of valence electrons.
Verified step by step guidance1
Understand that valence electrons are the electrons in the outermost shell (energy level) of an atom and are important for chemical bonding and reactivity.
Recognize that for main-group elements (those in groups 1, 2, and 13–18), the group number on the periodic table corresponds to the number of valence electrons. For example, elements in group 1 have 1 valence electron, group 2 have 2 valence electrons, and groups 13–18 have 3 to 8 valence electrons respectively.
Note that the period number indicates the highest occupied energy level (shell) but does not directly tell you the number of valence electrons.
Avoid using the atomic number minus the mass number to find valence electrons, as this calculation gives the number of neutrons, not electrons.
Therefore, to determine the number of valence electrons for a main-group element, identify its group number and use that as the count of valence electrons.
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