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.

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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