Electron Arrangement
Methods of predicting the
arrangement and location of
electrons in atoms
A. Lewis Dot Structures
valence electrons – e– in an atom’s
outermost orbitals (in highest energy level)
available for bonding; determine the
chemical properties of an element
electron-dot structure – consists of
element’s symbol surrounded by dots that
represent the atom’s valence e–
B. Electron Congifuration
s
p
1
2
3
4
5
6
7
f (n-2)
d (n-1)
6
7
© 1998 by Harcourt Brace & Company
C. Notations
Longhand Configuration
S 16e- 1s2 2s2 2p6 3s2 3p4
Core Electrons
Valence Electrons
C. Johannesson
Shorthand Configuration
Go up one row and over to the Noble
Gas.
Fill in the remaining e- in each sublevel
like normal.
S 16e-
[Ne] 3s2 3p4
Example - Germanium
1
2
3
4
5
6
7
[Ar]
2
4s
10
3d
2
4p
White Board Examples
Helium (He)
Fluorine (F)
Nitrogen (N)
Aluminum (Al)
Sulfur (S)
Homework
Do the Lewis dot structure and long and
short hand electron configuration for the
following elements:
Magnesium (Mg)
Silver (Ag)
Gold (Au)
Bromine (Br)
Europium (Eu)
D. Orbital Diagrams
This configuration gives more
detail as to where the electrons
are located.
orbital – region of high probability
of finding e–; maximum of 2 e–
per orbital
s sublevel = 1 orbital (2 e–)
p sublevel = 3 orbitals (6 e–)
d sublevel = 5 orbitals (10 e–)
f sublevel = 7 orbitals (14 e–)
Ex: Oxygen
E. General Rules
Pauli Exclusion Principle
Each orbital can hold TWO electrons
with opposite spins.
E. General Rules
Hund’s Rule
Within a sublevel, place one e- per
orbital before pairing them.
E. General Rules
Aufbau Principle
Electrons fill the
lowest energy
orbitals first.
White Board Examples
Indium (In)
Selenium (Se)
Sulfur (S)
Aluminum (Al)
Homework
Do the orbital diagram for the following
elements:
Magnesium (Mg)
Bromine (Br)
Phosphorus (P)
Neon (Ne)