Electron ConfigurationElectron Configuration

Quantum NumberQuantum Number

Number that specifies the properties of the atomic orbitals

Tells us the distance from the nucleus and the shape of the orbital

Principal Quantum NumberPrincipal Quantum Number

Main level or shellThese are the Bohr energy levels

n = 1, n = 2, n = 3As n increases, the distance from the

nucleus increases

SublevelSublevel

Each main level is divided into sublevelsFour types of sublevels

s

p

d

f

Spherical

S orbitalsS orbitals

P orbitalsP orbitals

Dumbell shapedOne dumbell in each axis

P OrbitalsP Orbitals

D orbitalsD orbitals

F orbitalsF orbitals

OrbitalOrbital

Each sublevel is made of orbitalsEvery orbital can hold 2 electrons

s – 1 orbital – 2 electrons p – 3 orbitals – 6 electrons d – 5 orbitals – 10 electrons f – 7 orbitals – 14 electrons

Main Level

Sublevel # orbitals

# e in sublevel

Total e

         

         

         

         

Electron ConfigurationElectron Configuration

Arrangement of electrons in an atomAufbau Principle – electrons fill into an

atom starting with the lowest energy levels

Electron Configuration PolkaElectron Configuration Polka

F:\Documents\electron configuration.avi

Electron SpinElectron Spin

Way which the electrons rotate on their axisPauli Exclusion Principle – in order for two

electrons to occupy the same orbital, they must have opposite spin

Write configuration for

C

S

Higher OrderHigher Order

There are exceptions to the order of filling as you move to higher levels

Br

Valence ElectronsValence Electrons

Electrons in the last main energy levelThese are the electrons involved in

chemical reactionsThere are a maximum of 8 valence

electrons

How to find valence eHow to find valence e--

Write configuration and count electrons in last main energy level

Examples: Find valence electrons for

C

Fe

Cl

Draw Dot StructureDraw Dot Structure

C

Fe

Cl

Periodic TablePeriodic Table

Demitri MendeleevDemitri Mendeleev

First to publish a chart of the elementsArranged by increasing atomic mass with

similar elements in columns

Moseley’s TableMoseley’s Table

He suggested that the elements are arranged by atomic number rather than atomic mass

Periodic Law – chemical and physical properties are periodic functions of their atomic numbers

Table PropertiesTable Properties

Horizontal Rows are called PeriodsVertical Columns are called Groups or

FamiliesFor every group or family, the electron

arrangement is the same

Configuration from the TableConfiguration from the Table

Group tells end configuration, period tells tells the highest energy level

Ca in group 2 period 4 so it ends in 4s2

BlocksBlocks

Chart is broken into blocks based on the orbitals they fill last

Groups 1 and 2 fill s last – called s blockGroups 3 –12 called d blockGroups 13 – 18 called p blockBottom two rows are the f block

Name the element with the Name the element with the following end configurationfollowing end configuration

5s1

2s22p3

4s23d6

3s23p6

6s25d9

http://modelscience.com/PeriodicTable.html