What are valence electrons?

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Valence electrons are the electrons in the last energy shell or the outermost shell on the atom. These electrons are the ones that participate in the chemical reactions. We can determine the valence electrons based on their position on the periodic table. The following are some examples of atoms with their respective valence electrons:

Na = 1

Mg = 2

Al = 3

C = 4

N = 5

O = 6


This is generally applied in s and p groups in the periodic table. Elements in the transition metals (d group) sometimes can have valence electrons available in their inner shell. 


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