**Electrons**

Electrons are found in specific circular paths, or orbits around the nucleus. Each electron has a fixed energy that is called its

energy level.

Bohr Says:

Can you go up a ladder without ever touching a rung?

NO! You need to move your legs very specific distances in order to make contact with the rungs to progress up or down the ladder.

Electrons can move between energy levels, much like we climb a ladder. Electrons need just the right amount of energy to go from one energy level to the next. This amount of energy required to move an electron from one energy level to the next is called a

QUANTUM

Energy of Electrons:

The amount of energy an electron gains or loses in an atom is not always the same. The higher energy levels are closer together, so there is less energy required to travel from one energy level to another energy level.

OOPS!

Bohr 's work never accounted for the energies absorbed or emitted by atoms with more than one electron

Schrodinger Says:

My calculations indicate the energies of electrons, but no exact path that an electron will travel. Probablity indicates where electrons are likely to be located.

..

Quantum Mechanical Model:

Schrodinger devised and solved mathmatical equations describing the behavior of electrons...His calculations led to the

Quantum Mechanical Model

The

Quantum Mechanical Model

determines the allowed energies an electron can have and how likely it is to find electrons in various locations around the nucleus of an atom.

..

Do you know exactly where the windmills blades are in any given moment?

NOT exactly

, but you can estimate the location using probability.....This is what Schrodinger's equation does for determining the location of electrons.

Electron Cloud

The electron cloud represents the locations where electrons are likely to be found.

**Atomic Orbitals**

Principal Quantum Numbers

(n): describe the energy level (n=1,2,3,4...)

For each energy level (n),

atomic orbitals

describe the probability of finding an electron at various places around the nucleus.

Orbitals can have different shapes and energies at the different energy levels

Sublevels and Orbitals

s-sublevel: holds a total of

2 electrons

in 1 orbital

p-sublevel: holds a total of

6 electrons

in 3 orbitals

d-sublevel: holds a total of

10 electrons

in 5 orbitals

f-sublevel: holds a total of

14 electrons

in 7 orbitals

Electron Configuration

: The ways in which electrons are arranged in various orbitals around the nuclei of atoms.

The periodic table defines the locations of electron in its format!

Row # = principal quantum number (n) or energy level

Block: defines orbital shape

1

2

3

4

5

6

7

N=

S-Block

p-Block

d-Block

f-Block

Writng electron configuration:

energy level

sublevel/orbital

number of electrons found in location

**1**

s

s

2

Three Rules define the electron configurations of atoms:

Aufbau Principle

: electrons occupy the orbitals of the lowest energy first.

Pauli Exclusion Principle

: an orbital may describe at most 2 electrons.

Spin

is a quantum mechanical property of electrons and may thought to be clockwise or counterclockwise...represented by arrows.

Hund's Rule

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

Ge

1s 2s 2p 3s 3p 4s 3d 4p

2

2

2

2

6

6

10

2

What does Sheldon have to say about the electron?