timberlake lectureplus 2000 subshells and orbitals

Timberlake LecturePLUS 2000

Subshells and Orbitals


Quantum Mechanics

Describes the arrangement of electrons in atoms in terms of:Main or principal energy levels (n)Energy subshellsOrbitals (space occupied within the

atom)


Principal Energy Levels (n)

Contain electrons that areClose in energySimilar distance from nucleusHave values of n = 1, 2, 3, 4, 5, 6…..Maximum number of electrons = 2n2

n =1 2(1)2 = 2

n =2 2(2)2 =8

n=3


Energy Levels (Shells)

• A group of electrons in an atom all having the same principal quantum number (n)

n = 1, 2, 3, …

• The first shell (n = 1) is lowest in energy, 2nd level next and so on 1<2<3<4

• The number of electron in each shell is limited to 2n2

n = 1 2n2 = 2

n = 2 2n2 = ____


Energy Levels for Electrons

Some possible electron transitions for the first three energy levels are shown below. The negative value means that the electron in the atom has a lower energy than a free electron

Energy Level Energy, E

n=3 ___________________ (-) 2.420 x 1019 J

n=2 __________________ (-) 5.445 x 1019 J

n=1 __________________ (-) 2.178 x 1018 J


Learning Check S1

A. What energy change (J) takes place when an electron in a hydrogen atom moves from the first (n=1) to the second shell (n=2)?

B. What energy change (J) takes place when the electron moves from the third shell to the second shell?


Solution S1

A. What energy change takes place when an electron in a hydrogen atom moves from the first (n=1) to the second shell (n=2)?

1.634 x 10-18 J of energy must be absorbed.

B. What energy change takes place when the electron moves from the third shell to the second shell?

(-5.445 x 10-19J ) - (2.2420 x 10-19 J) = -3.025 x 1019J will be emitted as electron falls from a higher to a lower energy state


Subshells

Energy sublevels within energy level

All electrons in a subshell have the

same energy

Designated s, p, d, f ..

Sublevel energy: s<p<d<f


Electron Locations

Main Energy Levels Sublevels

n=4 4s, 4p, 4d, 4f

n=3 3s, 3p, 3d

n=2 2s, 2p

n=1 1s


Sublevels in n = 1,2, 3

3d

n = 3 3p

3s

2p

n = 2 2s

n = 1 1s


Electrons Allowed

All electrons in the same sublevel have the same energy.

All 2s electrons have the same energy. All 2p electrons have the same energy which is slightly higher than the energy of the 2s electrons

s sublevel 2 electrons

p sublevel 6 electrons

d sublevel 10 electrons

f sublevel 14 electrons


Electron Configuration

List of subshells containing electronsWritten in order of increasing energySuperscripts give the number of electrons

Example: Electron configuration of neon

number of electrons

1s2 2s2 2p6

main shell subshell


Order of Filling

Total energy of a subshell = energy of the main shell + the subshell

The 4s energy < 3d energy4p ___3d ___ (finishes the n=3 shell)4s ___ (starts the n=4 shell)3p ___3s ___2p ___2s ___1s ___


Writing Electron Configurations

H 1s1

He 1s2

Li 1s2 2s1

C 1s2 2s2 2p2

S 1s2 2s2 2p6 3s2 3p4


Sublevel Blocks s1 s2 p1 p2 p3 p4 p5

p6

123 d1 - d10

456

f1 - f14


Find the element on the periodic table

Use the order of filling indicated across each period

Groups 1-2 = s level

Groups 3-8 = p level

Transition = d level

Lantanides = f level

Periodic Table and Electron Configuration


Learning Check S2

Indicate if each configuration is (1) correct or (2) incorrect for potassium. Give an explanation for selection of 1 or 2. Explain

why or why not?

A. 1s22s22p63s1 1 or 2

B. 1s22s22p63s23p6 1 or 2

C. 1s22s22p63s23p64s1 1 or 2

D. 1s22p83s1 1 or 2

E. 1s22s22p63s23p7 1 or 2


Solution E2

For phosphorus, indicate if each configuration is (1) correct or (2) incorrect. Explain why or why not.

A. 2, 2, 8, 5 2

B. 2, 8, 3 2

C. 2, 8, 5 1

D. 2, 6, 7 2


Learning Check S3

Using the periodic table, write the complete electronic configuration for each:

A. Cl

B. Sr

C. I


Solution S3

Using the periodic table, write the complete electronic configuration for each:

A. Cl

1s2 2s2 2p6 3s2 3p5

B. Sr

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

C. I

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5


Learning Check S4

A. The final two notations for Co are

1) 3p64s2

2) 4s24d7

3) 4s23d7

B. The final three notations for Sn are

1) 5s25p24d10

2) 5s24d105p2

3) 5s25d105p2


Solution S4

A. The final two notations for Co are

3) 4s2 3d7

B. The final three notations for Sn are

2) 5s2 4d10 5p2


Orbital

A 3 dimensional space around a nucleus in

which electrons are most likely to be found

Shape represents electron density (not a

path the electron follows)

Each orbital can hold up to 2 electrons.


s orbitals

1s 2s 3s


Three p Orbitals

px pz py


p subshell contains p orbitals


d orbitals


Learning Check S5

A. Number of electrons in a p orbital1) 1e 2) 1e or 2e 3) 3e

B. Number of orbitals in a p subshell1) 1 2) 2 3) 3

C. Number of orbitals in 4d subshell1) 1 2) 3 3) 5

D. Number of electrons (maximum) in a 3d subshell

1) 2e 2) 5e 3) 10e


Solution S5

A. Number of electrons in a p orbital

2) 1e or 2e

B. Number of orbitals in a p subshell

3) 3

C. Number of orbitals in 4d subshell

3) 5

D. Number of electrons in a 3d subshell

3) 10e

timberlake lectureplus 2000 subshells and orbitals

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