ATOMIC ORBITALS AND ELECTRON CONFIGURATIONS

Waves

Electrons behave like waves. The distance between corresponding points on

adjacent waves is the wavelength (). The number of waves passing a given point per unit of

time is the frequency ().

Waves

The number of waves passing a given point per unit of time is the frequency ().

The Nature of Energy

Max Planck explained it by assuming that energy comes in packets called quanta.

Quantum of energy is the amount of energy required to move an electron from one energy level to another energy level.

Moving to an Excited State

Ground Ground statestate

Excited Excited statestate

Incoming EnergyIncoming Energy

Outgoing EnergyOutgoing EnergyGround Ground

statestateExcited Excited statestate

Electron Energy

The electrons with the lowest energy are located nearest the nucleus.

Ground state electrons- electrons with their normal amount of energy for that energy level.

Excited state electrons- electrons that have absorbed energy and moved to a higher energy level farther from the nucleus.

Atomic Emission Spectrum

When atoms electrons lose energy they emit light

Each atom has a specific light pattern it gives off known as atomic emission spectrum.

More colors were seen than could be explained by Bohr’s Model.

Quantum Mechanics

Erwin Schrödinger developed a mathematical treatment into which both the wave and particle nature of matter could be incorporated.

It is known as quantum mechanics.

Heisenberg Uncertainty Principle: you can never know the speed and location of an electron simultaneously.

ENERGY LEVELS

Each row on the periodic table is a different principle energy level

Row 1 would be level 1 Row 2 would be level 2 and so on. Energy levels can be broken down into

sublevels, or different shaped orbital's.

ATOMIC ORBITALS

A region of space in which there is a high probability of finding an electron

4 different types of sub-levels S P D F

Sub-level S

Spherical Shape Sublevel s has 1 orbital Holds 2 electrons

Sub-Level P

Dumbbell Shaped has 3 orbital's Holds 6 electrons

Sub Level D

Clover Shaped has 5 orbital's Holds 10 electrons

Sub-Level F

7 orbital's Hold 14 electrons

ORBITAL DIAGRAMS

Orbital's will be shown as boxes Electrons will be shown as arrows Each orbital (box) can hold two electrons

(arrows)

Aufbau Principle- Electrons occupy the orbital's of lowest

energy first. Fill from bottom to top. Fill each set of orbital's before moving to a higher

orbital

Pauli Exclusion Principle-Two electrons in the same orbital

must have opposite spins

+

NN

NNSS

SS

-

The magnetic field effects of paired electrons help keep them in the same orbital.

Hund’s RuleElectrons occupy orbital's of the

same energy in a way that makes the number of electrons with the same spin direction as large as possible.

ORBITAL DIAGRAMS

1. Find the total number of electrons from the periodic table

2. Fill each orbital in the orbital filling diagram according to the three principals.

1. Fill from bottom to top2. Two electrons in the same orbital must have

opposite spins3. Pair electrons in the same orbital only when

there is no other option* Each orbital (box) can hold two electrons (arrows)

1s

2s

2p

3s

3p

3d

4s

4p

5s

Element: Lithium

1s

2s

2p

3s

3p

3d

4s

4p

5s

Element: Oxygen Atomic Number 8

1s

2s

2p

3s

3p

3d

4s

4p

5s

Element: Chlorine Atomic Number 17

1s

2s

2p

3s

3p

3d

4s

4p

5s

Element: Strontium Atomic Number 38

WRITING ELECTRON CONFIGURATIONS FROM ORBITAL DIAGRAMS Write the energy level and the symbol for

every sublevel occupied by an electron. Indicate the number of electrons occupying

that sublevel with a superscript.

1s1

Write each orbital in the same order that you filled in using the orbital filling diagram

1s

Writing the Condensed method for electron configuration

Condensed method is a short hand way to write electron configurations.

Consists of electron configuration of the valence electrons and the symbol of the noble gas from the previous period in brackets.

Condensed Method

1s2 2s2 2p6 3s2 3p3

1s2 2s2 2p6 3s2 3p6 4s2 3d6

[Ne] 3s2 3p3

[Ar] 4s2 3d6

Periodic Table

We fill orbitals in increasing order of energy.

Different blocks on the periodic table, then correspond to different types of orbitals.

Some Anomalies

Some irregularities occur when there are enough electrons to half-fill s and d orbitals on a given row.

Some Anomalies

For instance, the electron configuration for copper is

[Ar] 4s1 3d5

rather than the expected

[Ar] 4s2 3d4.