Electron Configuration

Electron ConfigurationElectron ConfigurationWhat is it?

◦A list of orbitals that contain electrons for an element.

◦Ex. 1s22s22p63s1

What are the different ways:◦Orbital notation _______

1s

◦Complete configuration 1s22s22p63s1

◦Abbreviated configuration(noble gas configuration) [He] 2s2

S orbitals are spherical

Lowest energy orbital

P orbitals are dumbell shaped

D orbitals

F orbitals (highest energy orbital level)

Rules of Electron Rules of Electron ConfigurationConfiguration1. Afbau principle

◦ An electron occupies the lowest energy orbital that can receive it.

2. Pauli exclusion principle◦ No two electrons in the same atom can

have the same four quantum numbers.3. Hund’s rule

◦ Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron and all electrons in singly occupied orbitals must have the same spin state.

NotationsNotationsOrbital Notation-

◦An unoccupied orbital is represented by ____

◦An orbital containing one electron is represented by ______

1s

◦An orbital containing two electrons is represented by _______

1s

Electron Configuration Notation◦1s2 2s2 2p6

StepsSteps1. determine the number of

electrons to be “addressed”.2. Look at the template or periodic

table and “count”3. You must fill “up” arrows in the

orbitals before filling “down” arrows. 4. The order of filling is 1s, 2s, 2p,

3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p (these are lowest energy to highest)

Blocks on the periodic Blocks on the periodic tabletableCan you find a pattern

Electron configuration Electron configuration practicepractice

Additional itemsAdditional itemsIsoelectric

◦When these atoms lose or gain electrons, they would have the same number of electrons.

Outer shell configuration◦Valence electrons orbitals and

placementDiamagnetic

◦When all of the electrons in orbitals are paired (up spin and down spin). If one is unpaired it is called paramagnetic)

Quantum Theory and Quantum Theory and Electron ConfigurationElectron Configuration

Quantum model of the Quantum model of the atom atom Quantum theory of an atom

◦A theory that uses mathematical equations to describe wave properties of electrons and other small particles.

Quantum Numbers◦These numbers completely describe

orbitals.

Quantum numbersQuantum numbers4 sets of numbers

house #, street, city, zip codearea code, prefix, number,

extension1. Principal quantum number2. Angular momentum

quantum number3. magnetic quantum number4. spin quantum number

Principal Quantum Principal Quantum NumberNumberSymbolized by nIndicates the energy level of the

electronAs n increases the electron’s

energy and its distance from the nucleus increase.

1-7

Angular Momentum Quantum Angular Momentum Quantum NumberNumberSymbolized by lIndicates the shape of the orbital

in a specific energy level.l = n-1For l=0, s orbital (spherical)For l=1, p orbital (dumbbell)For l=2, d orbitalFor l=3, f orbital

Magnetic Quantum Magnetic Quantum NumberNumberSymbolized by mM numbers are whole, including 0

from –l to +l.Indicates the orientation of an

orbital around the nucleus. ◦S has only 1 possible orientation◦P has 3 orientations◦D has 5 orientations◦F has 7 orientations

Spin Quantum NumberSpin Quantum NumberValues are +1/2 and -1/2 Indicates direction of spin2 electrons that are occupying

the same orbital have to have opposite spins.