Quantum Numbers

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Presentation Description

This lesson describes the use of quantum numbers to identify an electron's location, as well as describes the valid values that can be used for each quantum number.

Presentation Transcript

Quantum Numbers:

Quantum Numbers Set of 4 quantum numbers n, l , m, s “n” – 1 st quantum number “Principal quantum number” – main energy levels n can = 1, 2, 3,… Max number of electrons in a main energy level = 2n 2

Energy Sublevels:

Energy Sublevels “ l ” – 2 nd quantum number Describes the sublevels within each energy level # of sublevels in a main level = n Lowest sublevel  s ( l = 0 ) Second sublevel  p ( l = 1 ) Third sublevel  d ( l = 2 ) Fourth sublevel  f ( l = 3 ) l can = 0  “n-1”

Orbitals:

Orbitals “s” sublevel can hold 1 pair of electrons (2) “p” sublevel can hold 3 pair of electrons (6) “d” sublevel can hold 5 pair of electrons (10) “f” sublevel can hold 7 pair of electrons (14) The space occupied by one pair of electrons is called an orbital (3 rd Quantum Number = “m”) m can = “- l ”  “+ l ”

Electrons are like finicky hotel guests…:

Electrons are like finicky hotel guests… …they fill in the best possible (least energetic) locations first. This is known as the Aufbau principle. Electrons will go one to a bunk (orbital) before they pair up

Pauli Exclusion Principle (PEP):

Pauli Exclusion Principle (PEP) No two electrons in an atom have the same set of four quantum numbers. “n” describes electron cloud size “ l ” describes the shape of the cloud ( type of sublevel ) “m” describes the direction of the cloud in space

The last quantum number – “s”:

The last quantum number – “s” “s” – 4 th Quantum Number Distinguishes between electrons in the same orbital Describes the spin of the electron (clockwise or counterclockwise) Possible values for “s”: + ½ = clockwise spin (“spin up”) - ½ = counterclockwise spin (“spin down”)

PowerPoint Presentation:

“n” – Principal Quantum Number values from 1  infinity (mostly only 1-7) “ l ” – Energy Sublevel Number - values from 0  “n-1” “m” – Orbital Quantum Number - values from “– l ”  “+ l ” “s” – Spin Quantum Number - value = + ½ or -½

For example:

For example Hydrogen 1s ____ Helium 1s ____ Lithium 2s ____ Nitrogen 2p ____ ____ ____ Oxygen 2p ____ ____ ____ 1,0,0,+1/2 1,0,0,-1/2 2,0,0,+1/2 2,1, 1,+1/2 2,1,-1,-1/2