Valence Electrons

Atomic Orbitals

An atomic orbital is a region of space around the nucleus of an atom where there is a high probability of finding an electron

Electrons in Each Orbital

The orbital closest to the nucleus is the first orbital

• The first orbital holds a maximum of 2 electrons

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The rest of the orbitals hold a maximum of 8 electrons

• The number of orbitals is determined by the element’s period on the periodic table

More electrons =

more orbitals =

more energy

Valence Electrons

Valence electrons are the electrons present in the outermost orbital of an element

• An atom’s chemical behavior is mostly determined by the valence electrons

The number of valence electrons is determined by the group number on the periodic table

​

Group 1 = 1 V.E.

Group 2 = 2 V.E.

​

Groups 13-18:

Group # - 10

Ex:

Group 14 - 10 = 4 V.E.

The Octet Rule

The octet rule states that atoms with 8 electrons in their outer orbital are stable.

• Atoms will lose or gain electrons until their outermost orbital has 8 electrons
• Changing the atom’s electron count is how an atom becomes an ion

Mg

12

2

2

2+

Cl

17

7

1

1-