Period(rows)

Group or Family(columns)

The discovery of the STM's ability to image variations in the density distribution of surface state electrons created in the artists a compulsion to have complete control of not only the atomic landscape, but the electronic landscape also. Here they have positioned 48 iron atoms into a circular ring in order to "corral" some surface state electrons and force them into "quantum" states of the circular structure. The ripples in the ring of atoms are the density distribution of a particular set of quantum states of the corral. The artists were delighted to discover that they could predict what goes on in the corral by solving the classic eigenvalue problem in quantum mechanics -- a particle in a hard-wall box.

Principal Energy LevelGenerally symbolized by n, it denotes the shell (energy level) in which the electron is located.

Number of electrons that can fit in a shell:

2n2

Energy Level 1 can hold:

2e-

Energy Level 2 can hold:

8e-

Energy Level 3 can hold:

18e-

Energy Level 4 can hold:

32e-

Energy Level 1 can hold:

2e-

Energy Level 2 can hold:

8e-

Energy Level 3 can hold:

18e-

Energy Level 4 can hold:

32e-

Things to remember:•The element’s period # = the # of energy levels•There can only be 2 e- in the first energy level•When levels 2-7 are on the OUTSIDE, they can only hold a maximum of 8 e-.

Energy Level 1 can hold:

2e-

Energy Level 2 can hold:

8e-

Energy Level 3 can hold:

18e-

Energy Level 4 can hold:

32e-

Sublevels• There are 4 sublevels

– s (has 1 orbital)– p (has 3 orbitals)– d (has 5 orbitals)– f (has 7 orbitals)

• Each orbital can hold 2 electrons

How many electrons can each sublevel hold?

Can hold 2 e-

Can hold 6 e-

Can hold 10 e-

Can hold 14 e-

Orbital shapes are defined as the surface that contains 90% of the total electron probability.

An orbital is a region within an atom where thereis a probability of finding an electron. This is a probability diagram for the s orbital in the first energy level…

The s orbital has a spherical shape centered around the origin of the three axes in space.

s orbital shape

s sublevelshave 1 orbital

There are three dumbbell-shaped p orbitals in each energy level above n = 1, each assigned to its own axis (x, y and z) in space.

P orbital shape

Things get a bit more complicated with the five d orbitals that are found in the d sublevels beginning with n = 3. To remember the shapes, think of “double dumbells”

…and a “dumbell with a donut”!

d orbital shapes

Shape of f orbitals

• Click on the link below to see orbitals added one at a time:

• orbital shapes and positions, one at a time

Writing Electron Configurations

3p4

Principal Energy Level

Sublevel

# of e-Describes e- location.

Electron configuration of the elements of the first three series

Orbital Notation• Tell where electrons are arranged

in s, p, d, and f sublevel orbitals in each level around the nuclei of atoms.

• Use boxes to represent orbitals• Use or to represent e-

Aufbau Principle• Electrons occupy

lowest energy orbitals first

Like This

Pauli Exclusion Principle

Only two electrons can occupy one orbital… and they must have opposite spin.

Wolfgang Pauli

Like This p

orbitals

Hund’s Rule• One electron enters each orbital

until all the orbitals contain one electron with the same spin direction…

…then they pair up.

Orbital filling table

Irregular configurations of Cr and Cu

Chromium steals a 4s electron to half fill its 3d sublevel.

Copper steals a 4s electron to FILL its 3d sublevel

Wave-Particle Duality

His son, George Thomson won the Nobel prize for describing the wave-like nature of the electron.

The electron is an energy wave!

The electron is a particle!

JJ Thomson won the Nobel prize for describing the electron as a particle.

The Wave-like Electron

Louis deBroglie

The electron propagates through space as an

energy wave. To understand the atom, one

must understand the behavior of

electromagnetic waves.