The e- is found inside a blurry “electron cloud” An area where there is a chance of finding an electron. Only found with 90% accuracy in the area.

ELECTRONCONFIGURATION

THE QUANTUM MECHANICAL MODEL

The e- is found inside a blurry “electron cloud”

An area where there is a chance of finding an electron.

Only found with 90% accuracy in the area

WHERE CAN WE FIND ELECTRONS?

Each element has its own e- configuration for its ground state No charges

We base them on where the LAST e- is placed

IT’S LIKE AN ADDRESS…

State – city – street – house # State is called the Principle Energy level City is called the sublevel Street is called the orbital House # is the e- spin direction

PRINCIPLE ENERGY LEVELS

We have 1-7 Highest occupied ground state energy level =

PT period # Main energy levels Bohr found

SUBLEVELS

Each energy level has increasing number of sublevels Level 1 has 1 sublevel Level 2 has 2 sublevels Level 3 has 3 sublevels And so on….

Though 7 major levels…only 4 main sublevels are needed to describe existing atoms

SUBLEVEL

Sublevels are distinguished by the shape of orbitals in them

There are currently four of them s p d f

ORBITALS

In each sublevel there are specific orbitals An Orbital is a 3-D region in space an e- can

be found Does not have “hard and fast” boundaries

See next slide

Each orbital can hold only 2 e- Mathematically found through wave function

WHAT’S GOING ON…

S - SUBLEVEL

1 orbital in this sublevel Sphere shape Total 2 e- possible Same shape in each

level…just bigger Found in ALL energy

levels

p - SUBLEVEL

3 orbitals in this sublevel Dumbbell shaped Total 6 e- Found in Energy Level 2 or Higher Node between each half of each orbital

Intermediate area between high probability areas

d - SUBLEVEL

5 orbitals in this sublevel Clover shape Total 10 possible e- Found in Energy Level 3 or higher.

f - SUBLEVEL

7 orbitals in this sublevel Total 14 e- possible Complex shape Found in Energy Level 4 or higher

ENERGY - SUBLEVEL

Energy Level Sublevels

1 s

2 s, p

3 s, p, d

4 s, p, d, f

5 s, p, d, f, g

6 s, p, d, f, g, h

7 s, p, d, f, g, h, i

We will only commonly use s, p, d, and f!!

HOW WE WRITE WHERE E- ARE

State – city – street – house # State is called the principle E level City is called the sublevel Street is called the orbital House # is the e- spin direction

pd

f

1s

4

2

3

5

8 e-

2 e-

18 e-

32 e-

nucleus

Incr

easi

ng e

nerg

y

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

1s

2s

3s

4s

5s6s

7s

2p

3p

4p

5p

6p

3d

4d

5d

7p 6d

4f

5f

1s2=

1s

ELECTRON CONFIGURATION RULES

The way electrons are arranged in atoms. Aufbau principle- electrons enter the

lowest energy first. Must fully fill before move to next This causes difficulties because of the

overlap of orbitals of different energies.

RULES CONTINUED

Pauli Exclusion Principle- no 2 e- can have same set of 4 quantum # at most 2 electrons per orbital - different spins!!

Hund’s Rule- “up, up, up before down, down, down” All orbitals need to be filled w/one “up” spin

(positive--clockwise) before any in the sublevel is filled with a “down” spin (negative--counterclockwise)

DRAWING ORBITAL NOTATION

A box is used to represent each orbital.

Arrows are used to represent each electron.

**remember opposite spins.

Example: the orbital notation for carbon is:

2s1s 2p

ORBITAL NOTATION

Lets try a few: Orbital Notation for O

O = 8 e-

Orbital Notation for Cl Cl = 17e-

1s 2s 2p

1s 2s 2p 3s 3p

Electron Configuration

1s2# of electrons

PrincipleEnergy Level sublevel

3

Interpret the following Electron Configuration

p44 electrons

3rd Energy Levelp sublevel

WHEN DOING A CONFIGURATION…

Use the total number of e- Slowly place e- in order till run out of e- Example

B 5e- First 2 in 1s2…3 left over Next 2 can go is 2s2 …1 left over Last one goes in 2p, but since only 1 left it is 2p1

Final configuration 1s2 2s2 2p1

TRY A FEW

K Cl Fe Pb

ANSWERS K

1s2 2s2 2p6 3s2 3p6 4s1

Cl 1s2 2s2 2p6 3s2 3p5

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

Pb 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2

5d10 6p2

TONIGHT’S HOMEWORK

Write out the e- configuration for elements Hydrogen through and including Yttrium

DO NOW:

Box all things written with the HIGHEST PRINCIPLE energy level for each configuration of your homework Ex: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

Circle the LAST THING WRITTEN for each configuration of your homework Ex: 1s2 2s2 2p6 3s2 3p6 4s2 3d6

OUTERLEVEL (SHELL) CONFIGURATION

Everything is the outside/highest PRINCPLE ENERGY LEVEL Max is 8 e- total 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

EXAMPLES

Ga Ra Mn Se Am Br

EXAMPLES

Ga- 4s24p1

Ra- 7s2

Mn- 4s2

Se- 4s24p4

Am- 7s2

Br- 4s24p5

SUBLEVEL (SHELL) CONFIGURATION

The last thing written for the e- configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d6

Every element has its own ground level subshell configuration unique to itself

EXAMPLES

F Ca Al Pa Mo Xe

EXAMPLES

F- 2p5

Ca- 4s2

Al- 3p1

Pa- 5f3

Mo- 4d4

Xe- 5p6

NOBLE GAS CONFIGURATIONS

In order to save time and your hand when writing out electron configurations, one may use the Noble Gas Notation. A noble gas symbol is used in place of a

long list of electron configurations. Example: Ar: 1s2 2s2 2p6 3s2 3p6 = [Ar] Noble Gas Shorthand Configuration for Ca

Ca: [Ar] 4s2

EXAMPLES – NOBLE GAS CONFIGURATIONS

Sr  W

Hg

Cl

CHARGED ATOMS

Can do e- configurations for ions, but must make sure to note that that is what you are doing! Same way, just use the number of e- in the

ion involved