7 electrons

7/28/2019 7 Electrons

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Electron Orbitals

Cartoon courtesy of lab-initio.com


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Quantum MechanicalModel of the Atom

Mathematical laws can identify theregions outside of the nucleuswhere electrons are most likely to

be found.

These laws are beyond the scope of

this class


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Heisenberg Uncertainty Principle

The more certain you areabout where the electron is,the less certain you can beabout where it is going.

The more certain you areabout where the electron isgoing, the less certain you canbe about where it is.

One cannot simultaneously

determine both the positionand momentum of an electron.

WernerHeisenberg


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Quantum Numbers

Each electron in an atom has a unique set of4 quantum numbers which describe it.

Principal quantum number Angular momentum quantum number

Magnetic quantum number

Spin quantum number


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Electron Energy Level (Shell)

Generally symbolized

by n, it denotes theprobable distance ofthe electron fromthe nucleus. n is

also known as thePrinciple Quantumnumber

Number of electronsthat can fit in ashell: 2n2


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Orbital shapes are defined as the surfacethat contains 90% of the total electronprobability.

An orbital is a region within an energy levelwhere there is a probability of finding anelectron.

Electron Orbitals

The angular momentum quantum number,generally symbolized by l, denotes theorbital (subshell) in which the electron islocated.


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The sorbital(l = 0) has aspherical shape

centered aroundthe origin of thethree axes in

space.

sOrbital shape


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There are three dumbbell-shapedporbitals (l = 1) in each energy level aboven = 1, each assigned to its own axis (x, y

and z) in space.

porbital shape


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Things get a bit morecomplicated with the

five dorbitals (l = 2)that are found in the dsublevels beginning withn = 3. To remember

the shapes, think ofdouble dumbells

and a dumbell

with a donut!

dorbital shapes


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Shape of f (l = 3) orbitals


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EnergyLevel(n)

Sublevels inmain energy

level(n sublevels)

Number oforbitals per

sublevel

Number ofElectrons

per sublevel

Number ofelectrons permain energylevel (2n2)

1 s 1 2 2

2 sp 13 26 8

3 spd

135

2610

18

4 spdf

1357

261014

32

Energy Levels, Sublevels, Electrons


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Magnetic Quantum Number

The magnetic quantum number, generally

symbolized by m, denotes the orientation of theelectrons orbital with respect to the three axes inspace.


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Orbital filling table


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Electron SpinThe Spin Quantum Number describes

the behavior (direction of spin) of anelectron within a magnetic field.

Possibilities for electron spin:

1

2

1

2


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Pauli Exclusion Principle

Two electrons occupyingthe same orbital musthave oppositespins

WolfgangPauli


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Element Configuration

notation

Orbital notation Noble gas

notation

Lithium 1s22s1

____ ____ ____ ____ ____1s 2s 2p

[He]2s1

Beryllium 1s22s2

____ ____ ____ ____ ____1s 2s 2p

[He]2s2

Boron 1s22s2p1

____ ____ ____ ____ ____1s 2s 2p

[He]2s2p1

Carbon 1s22s2p2____ ____ ____ ____ ____

1s 2s 2p

[He]2s2p2

Nitrogen 1s22s2p3

____ ____ ____ ____ ____

1s 2s 2p

[He]2s2p3

Oxygen 1s2

2s2

p4

____ ____ ____ ____ ____1s 2s 2p

[He]2s2

p4

Fluorine 1s22s2p5

____ ____ ____ ____ ____1s 2s 2p

[He]2s2p5

Neon 1s22s2p6

____ ____ ____ ____ ____1s 2s 2p

[He]2s2p6


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Exclusion Warning!

Assigning quantum numbers to electronshas been exluded and will not be tested!

The following slides are purely for yourentertainment


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Assigning the Numbers The three quantum numbers (n, l, and m) areintegers.

The principal quantum number (n) cannot bezero.

nmust be 1, 2, 3, etc. The angular momentum quantum number (l)can be any integer between 0 and n - 1.

For n= 3, l can be either 0, 1, or 2. The magnetic quantum number (ml) can be anyinteger between -l and +l. For l = 2, mcan be either -2, -1, 0, +1, +2.


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Quantum numbers for the first four levels of orbitals in the hydrogen atom

n l Orbitaldesignation

ml # oforbitals

1 0 1s 0 1

2 0 2s 0 1

1 2p -1, 0, 1 3

3 0 3s 0 1

1 3p -1, 0, 1 3

2 3d -2, -1, 0, 1, 2 5

4 0 4s 0 1

1 4p -1, 0, 1 3

2 4d -2, -1, 0, 1, 2 5

3 4f -3, -2, -1, 0, 1, 2, 3 7

7 electrons

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