•REMINDER: STUDY GROUP ASSIGNMENT THIS WEEK

•LAB THIS WEEK

•ELECTRON ORBITALS

October 26, 2009

Visible Spectroscopy

Heisenberg Uncertainty Principle

We can’t know both the exact location and the energy of a particle

For electrons => We know the energy, so we don’t know the location very well

Schrödinger’s Model of Hydrogen

Electrons act as standing waves

Wave behavior is described by a wave function: ψ Certain wave functions are allowed ψ2 describes the probability of finding the electron in

a particular spot (aka, electron density)

Here’s what a probability density looks like…

(A bit simplified)

…but what does it mean?

o-r/a2 2 = x e

Orbitals

Each wave function describes a shape = Orbital Where an electron can be found/exist Organized into main shells and subshells

Number of orbitals is different for each subshell type: s = 1 orbital p = 3 orbitals d = 5 orbitals f = 7 orbitals

Size and Energy(n=1, 2, 3, … )

Shape(s, p, d, f, … )

1s ___11

2p ___ ___ ___2s ___22

3d ___ ___ ___ ___ ___

3p ___ ___ ___3s ___

33

ENERGY

•1, 2, and 3 correspond to the major energy levels (main shells)

•At the same main shell level, a p orbital will be at a higher energy than an s orbital

4f ___ ___ ___ ___ ___ ___ ___ 4d ___ ___ ___ ___ ___ 4p ___ ___ ___

4s ___

44

What type of orbital is this?

1 2 3 4

25% 25%25%25%1. s2. pz

3. dxy

4. dxz

10

Which type of orbital can’t exist?

1 2 3 4

25% 25%25%25%1. 1px

2. 2px

3. 2s4. 3dxy

10

NODES- Where electrons don’t go

Spherical Nodes

Hydrogen

You too can play with hydrogen…

http://homepages.ius.edu/kforinas/physlets/quantum/hydrogen.html

Quantum # Rules

There are four different quantum numbers: n, l, ml, and ms

n, l, and ml are integers n cannot be zero l can be 0 to n-1 ml can be anything from –l to l Ms can be +½ or -½

Quantum Numbers and Orbitals

Rules for filling orbitals

1. Pauli Exclusion PrincipleNo two electrons can have the same 4 quantum numbersAn orbital has a maximum of 2 electrons of opposite spin

2. Aufbau/Build-up PrincipleLower energy levels fill before higher energy levels

3. Hund’s RuleElectrons only pair after all orbitals at an energy level have

1 electron

4. Madelung’s RuleOrbitals fill in the order of the value of n + l

Orbital Filling Order