Electron Configuration

Mapping the electrons

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)

Heisenberg uncertainty principle

it is impossible to determine simultaneously both the position and velocity of an electron or any other particle with any great degree of accuracy or certainty.

Erwin Schrodinger Formulated equation that describes behavior and

energies of subatomic particles. Incorporates both particle and wave behavior in

terms of wave function: is proportional to the probability of finding an

electron. Leads to Quantum Mechanics: we cannot pinpoint an

electron in an atom but we can define the region where electrons can be in a particular time……… called a Probability map….a 3-dimensional area in space called an ORBITAL

Principal Quantum Number, n

Indicates main energy levelsn = 1, 2, 3, 4…

Each main energy level has sub-levels

Energy Sublevels

s p d f g

The principle quantum 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 sublevel0 s1 p2 d3 f4 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

Visualizing the orbitals

Orbitals in Sublevels

Sublevel # Orbitals # electronss 1 2p 3 6d 5 10f 7 14g 9 18

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.

Orbital Diagram

Filling Order diagram

-Pauli Exclusion Principle(Wolfgang Pauli, Austria, 1900-1958)-Electron Spin Quantum Number

An orbital can hold only two electrons and they must have opposite spin.

Electron Spin Quantum Number (ms):

+1/2, -1/2

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.

Orbital Diagram for Hydrogen

OrbitalDiagram for Helium

Orbital Diagram for Lithium

Orbital Diagram for Beryllium

Orbital Diagram for Boron

OrbitalDiagram for Carbon

Orbital Diagram for Nitrogen

Orbital Diagram

Notations of Electron Configurations

Standard Shorthand

Orbital Diagram for Fluorine

Standard Notation of Fluorine

Main Energy

Level

Numbers

1, 2, 2Sublevels

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

Blocks in the Periodic Table