Valence Electrons

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A chemical reaction involves either electron removal, electron addition, or electron sharing. The path a specific element will take depends on where the electrons are in the atom and how many there are.

Valence electrons are the electrons in the highest occupied principal energy level of an atom. In the second period elements, the two electrons in the 1s1s sublevel are called inner-shell electrons and are not involved directly in the element's reactivity or in the formation of compounds.

Lithium has a single electron in the second principal energy level and so we say that lithium is one valence electron. Beryllium has two valence electrons.

the second principal energy level consists of both the 2s2s and the 2p2p sublevels

In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in 2s22p62s22p6, has eight valence electrons.

Summary

Valence electrons are the outer-shell electrons of an atom.

Valence electrons determine the reactivity of an atom.

to tell how many electrons there are on a principal energy level, you use the formula 2n2 (two multiplied by N to the square) where N stands for the principal energy level

the quantum number is 4 numbers that are coming from the Schrodinger equation

N= energy level

goes from 1-7

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