More Electron Arrangement!

Examples:

Se 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴

Sn 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p²

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

HOEL (Highest Occupied Energy Level): energy level furthest from the nucleus that contains at least one electron

How to determine this using electron configuration?

~ largest non-exponent number

Se 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ HOEL = 4

Sn 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p² HOEL = 5

Hg 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ HOEL = 6

Valence Electrons: electrons in the HOEL

How to determine this using electron configuration?

~ add up exponents of terms in HOEL

Se 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
HOEL = 4 Valence electrons = 2 + 4 = 6

Sn 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p²
HOEL = 5 Valence electrons = 2 + 2 = 4

Hg 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰
HOEL = 6 Valence electrons = 2

Noble Gas Configuration: shortcut for electron configuration

How is it written?

~ [ symbol for noble has closest to element with lower atomic # ]

~ [after brackets] next number is the period that the element is located in

~ after that number, write “s”

~ continue electron configuration in diagonal rule order until appropriate # of
electrons is reached

*NOTE: ending of electron configuration and noble gas configuration should be the same*

Se 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
[Ar] 4s² 3d¹⁰ 4p⁴

^{18 20 30 34}

Sn 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p²

[Kr] 5s² 4d¹⁰ 5p²

^{36 38 48 50}

Hg 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰
[Xe] 6s² 4f¹⁴ 5d¹⁰

^{54 56 70 80}

Orbital Notation: drawing of how electrons are arranged in orbitals; will only need to do this for the HOEL

*NOTE: ___ = orbital h or i = electrons

Se 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ hi hi h h_
4s 4p

Sn 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p² hi h h __
5s 5p

Hg 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ hi
6s

Dot Diagrams: symbol represents nucleus and non-valence (“inner-shell”) electrons; dots around symbol represent valence electrons