Question

If each orbital can only hold 2 electrons, what about the valence electrons? Shouldn't there be eight?

Answer 1

There are multiple orbitals, that can each hold different numbers of electrons.

Explanation:

The s orbital can only hold 2.

p orbitals can hold 6

d orbitals can hold 10

f orbitals can hold 14

Valence electrons relate to the number of electrons in the outermost shell

Answer 2

Each orbital can only hold 2 electrons, but energy levels consist of multiple orbitals.

Explanation:

There are four types of sublevels: s, p, d, and f. A single orbital can only hold 2 electrons, but each sublevel contains different numbers of orbitals.

• s: 1 orbital (2 electrons)
• p: 3 orbitals (6 electrons)
• d: 5 orbitals (10 electrons)
• f: 7 orbitals (14 electrons)

Then there's energy levels, which contain different kinds of sublevels

• 1: s
• 2: s p
• 3: s p d
• 4: s p d f
• 5: s p d f
• 6: s p d f
• 7: s p d f

The valence electrons are simply the electrons in the highest energy level. So, if the first energy level is the valence level (H-He), there can be up to 2 valence electrons since there is only an s sublevel. If the second energy level is the valence level (Li-Ne), there can be up to 2+6=8 valence electrons since there is an s and a p sublevel. For all main group elements (i.e. not transition metals), this second case: 8 valence electrons, since they all fill up to their valence p orbitals. This is the simple case.

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