Electronic Structure

Orbitals to

Principal quantum numbers

• used to number the energy levels or quantum shells

Sub shell letters

• s

• p

• d

• f

How many electrons can an orbital hold?

Two electrons

S subshell

Orbitals: 1

Max no. Electrons: 2

p subshell

Orbitals: 3

Max no. Electrons: 6

d subshell

Orbitals: 5

Max no. Electrons: 10

f sub-shell

Orbitals: 7

Max no. Electrons: 14

Valence electron

the electrons in the outermost shell, or energy level, of an atom

General Exception concerning energy levels in shells

• 3d orbital has a higher energy level than the 4s orbital

• E.g electrons are filled in from 4s first, then 3d

• E.g electrons are lost from the 4s first then 3d

electronic configuration of Potassium

1s² 2s²2p⁶ 3s² 3p⁶ 4s¹

Exception to the electron configuration: Cr

[Ar] 3d⁵ 4s¹

• energetically more stable

Exception to the electron configuration: Cu

[Ar] 3d¹⁰ 4s¹

• energetically more stable