**Orbitals and Lewis dot notation**

Electron Configuration - arrangement of all electrons in that atom

Look up atomic number

Determine number of electrons

Consult arrow diagram to determine order to fill sublevels filling from lowing energy leveland increasing - Aufbau rule

Write electron configuration

2e- in s

6e- in p

10e- in d

14e- in f

Use superscripts to indicated how many electrons are in each orbital

Add up exponents to make sure you have the correct number of electrons

Abbreviated version - [noble gas] valence electrons

Quantum numbers - there are four of them

Principle quantum number (n)- energy level, which is always a whole number

"Shielding" effect- reduces electrostatic attraction between protons in the nucleus and the electrons in outer shells

Angular momentum quantum number (l) - indicates what sublevel the electron occupies where 0 = s, 1 = p, 2 = d, 3 = f

Magnetic quantum number (M subscript l) - spacial orientation of the orbital where different sublevels are indicated by positive and negative numbers

Fourth Quantum number

Spin quantum number (M subscript s) - indicated the "spin" direction of the electron in a particular orbital. Can be +1/2(counter-clockwise) or -1/2(clockwise)

Pauli's exclusion principle states that no two electrons in an atom can have the same exact set of four quantum numbers - only two electrons may occupy the same atomic orbital having opposite spins

Orbital Diagram

Make circles, boxes, or lines to indicate suborbitals

Fill up each orbital with a positive "spin" state before pairing up an electron with a negative spin

Hund's rule - the most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins

Angular momentum Quantum number

Lewis dot Notation

Valence - outermost shell of electrons

Try for Cations and anions

Octet rule - an atom other than hydrogen tends to form bonds until it is surrounded by eight valence electrons

Lewis structure - a representation of covalent bonding in which shared electron pairs are shown either as lines or as pairs of dots between two atoms, and lone pairs are shown as pairs of dots in individul atoms

General Rules

1. Each shell or principle level of a quantum number n contains n subshells

2. Each subshell l contains (2l +1) orbitals

3. No more than two electrons can be placed in each orbital.

4. The maximum number of electrons that an atom can have in a principle energy level is 2n^2

Paramagnetic - net unpaired spins and are attracted by a magnet (parallel)

Diamagnetic - do not contain net unpaired spins and are slightly repelled by a magnet (antiparallel)

Orbital Shapes

Electrons will primarily exist in this region about 90% of the time

Quantum Mechanics

The study of the motion of objects that are atomic or subatomic in size and thus demonstrate wave-particle duality

Can only gain or lose energy in discrete units called quanta

Heisenberg Uncertainty Principle- it is impossible to determine simultaneously both the positions and the velocity of a particle

Erwin Schrodinger (1887-1961)- Australian physicist used wave particle duality of the electron to develop and solve a complex mathematical equation that accurately describe the behavior of the electron in a hydrogen atom

Orbitals are created from these calculations

Quantum numbers- specify the properties of the atomic orbitals and the electrons in those orbitals

Electron Configuration-Valence Electrons and Exceptions

Take a close look at chromium and copper.

Any exceptions to the Aufbau Rule?

Exceptions?

Exceptions?

What trends do you notice?