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 Summary of Electron Configurations

The number of electrons in each sublevel

 sublevel # of electrons in each sublevel s 2 p 6 d 10 f 14 g 18

The Principal Energy Level (the #) only holds that # of sublevels.

 Principal Energy Level # of Sublevels sublevels 1 1 1s 2 2 2s  2p 3 3 3s 3p 3d 4 4 4s 4p 4d 4f 5 5 5s 5p 5d 5f 5g

Yes, the 5th energy level  holds 5 sublevels and that last one would be 5g.

Electrons add in energy order (Aufbau Principle) not energy level order.

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6

Maximum number of electron in an energy level  (2n2)

 Principal Energy Level  (n) sublevels electrons total electrons 1 1s 2 2 2 2s  2p 2 + 6 8 3 3s 3p 3d 2 + 6 +10 18 4 4s 4p 4d 4f 2 + 6 + 10 + 14 32 5 5s 5p 5d 5f 5g 2 + 6 + 10 + 14 + 18 50

or written like this  2-8-18-32-50

Maximum number of orbitals in an energy level  (n2)

 Principal Energy Level  (n) sublevels electrons total electrons total orbitals 1 1s 2 2 1 2 2s  2p 2 + 6 8 4 3 3s 3p 3d 2 + 6 +10 18 9 4 4s 4p 4d 4f 2 + 6 + 10 + 14 32 16 5 5s 5p 5d 5f 5g 2 + 6 + 10 + 14 + 18 50 25

Sublevels are broken down into orbitals

an orbital holds 2 electrons

Here is an animation of how the orbitals would look as you build out from the 1s.

Pauli Exclusion Principle

When we draw electrons, we use up and down arrows. So, if an electron is paired up in a box, one arrow is up and the second must be down.

Hund’s Rule

When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up.

 Mn 1s 2s 2p 3s 3p 4s 3d

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