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# Subshells and Orbitals - PowerPoint PPT Presentation

Subshells and Orbitals. Quantum Mechanics. Describes the arrangement of electrons in atoms in terms of: Main or principal energy levels (n) Energy subshells Orbitals (space occupied within the atom). Principal Energy Levels (n). Contain electrons that are Close in energy

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Timberlake LecturePLUS 2000

Describes the arrangement of electrons in atoms in terms of:

• Main or principal energy levels (n)

• Energy subshells

• Orbitals (space occupied within the atom)

Timberlake LecturePLUS 2000

Contain electrons that are

• Close in energy

• Similar distance from nucleus

• Have 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

Timberlake LecturePLUS 2000

• 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 = ____

Timberlake LecturePLUS 2000

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 1019 J

n=2 __________________ (-) 5.445 x 1019 J

n=1 __________________ (-) 2.178 x 1018 J

Timberlake LecturePLUS 2000

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?

Timberlake LecturePLUS 2000

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 1019J will be emitted as electron falls from a higher to a lower energy state

Timberlake LecturePLUS 2000

• 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

Timberlake LecturePLUS 2000

Main

Energy

Levels Sublevels

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

n=3 3s, 3p, 3d

n=2 2s, 2p

n=1 1s

Timberlake LecturePLUS 2000

3d

n = 3 3p

3s

2p

n = 2 2s

n = 1 1s

Timberlake LecturePLUS 2000

• 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

Timberlake LecturePLUS 2000

• List of subshells containing electrons

• Written in order of increasing energy

• Superscripts give the number of electrons

Example: Electron configuration of neon

number of electrons

1s2 2s2 2p6

main shell subshell

Timberlake LecturePLUS 2000

• Total energy of a subshell =

energy of the main shell + the subshell

• The 4s energy < 3d energy

4p ___

3d ___ (finishes the n=3 shell)

4s ___ (starts the n=4 shell)

3p ___

3s ___

2p ___

2s ___

1s ___

Timberlake LecturePLUS 2000

H 1s1

He 1s2

Li 1s2 2s1

C 1s2 2s2 2p2

S 1s2 2s2 2p6 3s2 3p4

Timberlake LecturePLUS 2000

s1 s2 p1 p2 p3 p4 p5 p6

1

2

3d1 - d10

4

5

6

f1 - f14

Timberlake LecturePLUS 2000

• 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

Timberlake LecturePLUS 2000

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

Timberlake LecturePLUS 2000

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

Timberlake LecturePLUS 2000

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

A. Cl

B. Sr

C. I

Timberlake LecturePLUS 2000

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

Timberlake LecturePLUS 2000

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

Timberlake LecturePLUS 2000

A. The final two notations for Co are

3) 4s2 3d7

B. The final three notations for Sn are

2) 5s2 4d10 5p2

Timberlake LecturePLUS 2000

• 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.

Timberlake LecturePLUS 2000

3s

2s

1s

Timberlake LecturePLUS 2000

px

pz

py

Timberlake LecturePLUS 2000

Timberlake LecturePLUS 2000

Timberlake LecturePLUS 2000

A. Number of electrons in a p orbital

1) 1e 2) 1e or 2e 3) 3e

B. Number of orbitals in a p subshell

1) 1 2) 2 3) 3

C. Number of orbitals in 4d subshell

1) 1 2) 3 3) 5

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

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

Timberlake LecturePLUS 2000

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