c_electron_config

11.1.3.1 understand and be able to work with a shell model of the atom: shell, sub-shell, orbital
11.1.3.2 recall the shapes of s, p, d, and f orbital (sets)
11.1.3.3 understand the rules for the filling of shells and sub-shells
11.1.3.4 recall the Aufbau (Kletchkovsky) principle as a mnemonic for the arrangement of electrons
11.1.3.5 be able to draw the electronic configuration for the first 36 elements
Learning objectives

Success criteria
explain the shell - subshell - orbital structure of the atom and relate it to quantum numbers
describe and sketch the shapes of s and p orbitals
identify the main principles of atomic orbital filling with electrons
state the electronic configuration of atoms and ions given the proton number and charge, using the convention 1s22s22p6 , etc.
construct the electronic configuration of atoms and ions in full and shorthand form

Electron Configuration
The way electrons are arranged around the
nucleus.

Quantum Mechanical Model
1920’s
Werner Heisenberg (Uncertainty Principle)
Louis de Broglie (electron has wave properties)
Erwin Schrodinger (mathematical equations using probability, quantum numbers)

Energy Levels
Indicates main energy levels
n = 1, 2, 3, 4…
Farther from nucleus = higher number
Each main energy level has sub-levels
s p d f

The Energy level number, n, determines the number of sublevels within the principle energy level.

Orbital Quantum Number, ℓ
(Angular Momentum Quantum Number)
Indicates shape of orbital sublevels
ℓ = n-1
ℓ sublevel
0 s
1 p
2 d
3 f
4 g

Orbital
The space where there is a high probability that it is occupied by a pair of electrons.
Orbitals are solutions of Schrodinger’s equations.

Orbitals in Sublevels
Sublevel # Orbitals # electrons
s 1 2
p 3 6
d 5 10
f 7 14
g 9 18
shapes

Three rules are used to build the electron configuration:
Aufbau principle
Pauli Exclusion Principle
Hund’s Rule

Aufbau Principle
Electrons occupy orbitals of lower energy first.

Aufbau Diagram

The diagonal rule

Hund’s Rule
In a set of orbitals, the electrons will fill the orbitals in a way that would give the maximum number of parallel spins (maximum number of unpaired electrons).
Analogy: Students could fill each seat of a school bus, one person at a time, before doubling up.

-Pauli Exclusion Principle
(Wolfgang Pauli, Austria, 1900-1958)
An orbital can hold only two electrons and they must have opposite spin.
Good NOT

Aufbau Diagram for Hydrogen

Aufbau Diagram for Helium

Aufbau Diagram for Lithium

Aufbau Diagram for Beryllium

Aufbau Diagram for Boron

Aufbau Diagram for Carbon

Aufbau Diagram for Nitrogen

Notations of Electron Configurations
Standard
Shorthand

Aufbau Diagram for Fluorine

Standard Notation
of Fluorine
Main Energy Level Numbers 1, 2, 2
Sublevels
Number of electrons
in the sub level 2,2,5
1s2 2s2 2p5

Shorthand Notation
Use the last noble gas that is located in the periodic table right before the element.
Write the symbol of the noble gas in brackets.
Write the remaining configuration after the brackets.
Ex: Fluorine: [He] 2s2 2p5