Unit 07? Orbital Diagrams and e- Configurations

Atomic Orbitals

  • A region in space in which there is a high probability of finding an e-.

  • The energy levels are represented by principal quantum numbers, n.

  • n = 1, 2, 3, 4, etc.

  • The principal quatum numbers indicate the relative size and energies of the atoic orbitals.

  • As n increases, the orbital becomes larger and the e- spend more time farther from the nucleus.

  • n specifies the atom;s major energy levels 9called principal energy levels)

  • The number of the princpal energy level is equal to the number of sublevels that it can contain.

Quantum #1 has 1 sublevel

  • Quantum #2 has 2 sublevels

  • Quantum #3 has 3 sublevels

  • Quantum #4 has 4 sublevels

  • Each energy sublevel corresponds to an orbital or a

different shape, which describes where the e- is likely

to be found.

  • 4 sublevels = 4 orbitals = s, p, d, and f

S Orbital

  • Spherical in shape

  • Lowest Energy level there is

  • 1 orientation in space (1 orbital)

  • Holdea a maximum of two e-

P Orbital

  • Dumbell shape

  • Has more energy than s

  • 3 orbitals (3 orientations in space)

  • Can hold a maximum of 6 e- (2/orbital)

  • n=2, # e- =2.718 8 (2 from s, 6 from p)

D Orbital

  • Complex shape

  • Has more energy than s and p orbitals

  • 5 orbitals (5 orientations in space and shape)

  • Can hold a max of 10 e-

  • n = 3, # of e- = 18

F Orbital

  • Complex shape

  • Orbital with the highest energy

  • 7 orbitals (orientations in space and shape)

  • Hold a max of 14 e-

  • n = 4, 32 e- total

Orbital Diagrams

  • e- fill orbitals of lowest energy first

  • Each orbital can be occupied by up to two electrons

  • Since each sublevel holds a different number of

orbitals, they hold a different number of total e-

  • The e- in any orbital spin in opposite directions

  • ↑ represents an e- spinning in one direction

  • ↓ represents an e- spinning in the other direction

  • e- will not pair until there is one e- in each orbital

● The element's location on the PT tells you how to

complete the orbital diagram.

● Remember the PT is divided into s, p, d, and f

blocks.

● Whichever block the element is located in, will tell

you the ending of your orbital diagram.

● To determine the specifics of the orbital diagram,

you use an Aufbau diagram to show you how the

e- fill the orbitals in terms of energy.

Aufbau Principle — CandyLand!

  • All orbitals in an energy sublevel are of equal energy

  • Energy sublevels within a principal energy level have different energies

  • e- occupy the orbitals of lowest energy first

  • e- occupy the s orbital, then p, and so on

Pauli Exclusion Principle

  • An atomic orbital can describe at most 2 e-

  • e- spin

  • In order to occupy an orbital, e- must have opposite spins

  • Arrows are used to represent the e- and their spin

Hund’s Rule — Busdriver!

  • e- eter each orbital one at a time until all tthe orbitals of that type have one e- with the same spin direction

Orbital Diagrams

  • If you complete your diagram sucessfully, then the number of arrows should equal the atomic number of the element.

  • You should also notice your diagram ended in the orbital based one what block the element is located.

  • Notice toy cannot pair e- until each orbital has at least one e- in it.

Checkpoint 02

Draw the orbital diagram for the following elements.

e- Configuration

  • The way electrons are arranged in the orbitals around the nucleus

  • Specific order

  • Also follows the 3 rules:

    • Aufbau principla

    • Pauli Exclusion Principle

    • Hund’s rule

How to Write e- Configurations

  • Materials - PT and Aufbau diagram

  • Locate the element on the PT

  • Use the aufbau diagram to know the principle quantum number for the orbitals

  • Fill the orbitals based on Pauli exclusion principle and Hund’s rule

Noble Gas Configuration

  • Shorthand version of e- configuration

  • Allows you to “start” and e- configuration from the closest Nobel gas and continue from there

  • The Nobel gas must come before the element on the PT

  • Find the Nobel gas that precedes the element

  • Write the Nobel gas in brackets

  • Start writing the e- configuration form the noble gas

Exceptions

  • Although the Aufbau rule accurately predicts the electron configuration of most elements, there are notable exceptions among the transition metals and heavier elements.

  • the reason these exceptions occurs is that some elements are more stable with fewer electrons in some sub shells and more electrons in others

  • Their configuration is more stable by having half filled sublevels than having the normal configuration

  • There are several different exceptions, but you will be responsible for knowing only 5

  • The five elements you need to know are chromium, molybdenum, copper, silver, and gold

  • When you look at their locations on the PT, you should notice they are in the transition metals

  • Chromium and molybdenum would have configurations that ended in d^4

  • However, it is more stable to have two half filled orbitals instead of one full s and and partial d

  • For copper, silver, and gold, they would normally end in d^9

    Again, it is more stable to have a filled d orbital and a half filled s orbital

  • So for chromium and molybdenum the ending would be s^1d^5

    For copper, silver, and gold the ending would be s^1d^{10}