Quantum Theory-based partly on Heisenberg’s Uncertainty Principle the position and the

momentum of a moving object cannot simultaneously be measured and known exactly

there is an inherent limitation to knowing both where a particle is at a particular moment and how it is moving in order to predict where it will be in the future

Hesisenberg Uncertainty Principle

-an electron is in an electron orbital– probability space where an electron can be found a certain percentage of the time as defined by Schrodinger’s equations

 

-An orbital can hold 2 electrons (this means the bigger the energy level, the more orbitals it has!).-Schrodinger’s equations (once all the mathematics has been done) describe where a particular electron is likely to be found

So, what do we know about where electrons are found in an atom???

Type of information

Label

What it represents How many options? How many e- can it hold?

Energy Level n Distance from the nucleus

n=1 through n=7 2n2

Sublevel l Shape of Orbitals n = 1 1 sublevel (s)n = 2 2 sublevels (s, p)

n = 3 3 sublevels (s, p, d)n = 4 4 sublevels (s, p, d, f)

Level 1 = ______Level 2 = ______Level 3 = ______Level 4 = ______Level 5 = ______

Magnetic lm Orientation of Orbital (which direction it is

pointing)

Depends on the number of sublevels.

p-orbitals follow the x, y, and z axes (one orbital per axis)

(each orbital can hold 2 electrons)

Spin ls How electron is spinning

Up = + ½ Down = - ½

The spinning of electrons generates an electric field.

For 2 electrons to occupy the same orbital they must

have opposite spin.

Shape of S- Orbitals

Shape of P-Orbitals

Shape of D- Orbitals

Quantum Theory Review:

1) According to the quantum theory, are electrons particles, waves, or both?

2) What are the 4 quantum numbers, and what do they describe?

Distribution of electrons around the nucleus

Aufbau Principle• Each electron occupies

the lowest energy orbital – i.e. Electrons are Lazy!

• All orbitals related to an energy level are of equal energy. – i.e. The three 2p orbitals

are the same energy level.

Hund’s Rule• Single electrons with the same spin must

occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals. – i.e. Electrons are unfriendly!

Analogy: Seats on a bus

Hund’s RuleExample

Pauli Exclusion Principle• A maximum of two electrons

may occupy a single orbital, but only if the electrons have opposite spins.

• spin-- Electrons have an associated “spin,” either one way or the other, like a top.

• These spins are called “spin up” and “spin down.”

Exceptions to filling order are copper, chromium and some others- because half-filled shells are more stable, so an atom may borrow an electron from next s shell to half fill a lower energy level.

Correct or Incorrect?

Complete the following diagram for Magnesium. How many electrons will a neutral atom of magnesium have? ____

If you were to summarize the information about Magnesium, how might you write it more simply?

HOMEWORK:

Complete “Practice- Orbital Notations & Electron Configurations”

DUE TOMORROW!!!

Apartment Rules Electron Rules

From the Bottom Up: Rooms must be filled from the ground floor up. Fill the one room on the first floor before starting to put new tenants on the second floor. Then fill the s room before the p rooms. At higher floors the order might change a bit.

Singles First: the owner of the building wants to have the tenants spread out as much as possible. For that reason singles are placed in rooms before couples. If couples must be placed into a room then all of the other rooms on that floor must already have a single in them.

Opposite Gender Only: When two people are placed in a room they must be of opposite genders. No men may room together and no women may room together. This is an arbitrary rule on the part of the owners: in a just world we wouldn’t have to follow it. But quantum mechanics has nothing to do with justice.

Apartment Analogy: What description would go in the right column?