Subshells and orbitals
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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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Subshells and Orbitals

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Subshells and orbitals

Subshells and Orbitals

Timberlake LecturePLUS 2000


Quantum mechanics

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)

Timberlake LecturePLUS 2000


Principal energy levels n

Principal Energy Levels (n)

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 =12(1)2 = 2

    n =22(2)2 =8

    n=3

Timberlake LecturePLUS 2000


Energy levels shells

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 = 12n2 = 2

    n = 22n2 = ____

Timberlake LecturePLUS 2000


Energy levels for electrons

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 1019 J

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

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

Timberlake LecturePLUS 2000


Learning check s1

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?

Timberlake LecturePLUS 2000


Solution s1

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

Timberlake LecturePLUS 2000


Subshells

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

Timberlake LecturePLUS 2000


Electron locations

Electron Locations

Main

Energy

LevelsSublevels

n=44s, 4p, 4d, 4f

n=33s, 3p, 3d

n=22s, 2p

n=11s

Timberlake LecturePLUS 2000


Sublevels in n 1 2 3

Sublevels in n = 1,2, 3

3d

n = 33p

3s

2p

n = 22s

n = 11s

Timberlake LecturePLUS 2000


Electrons allowed

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

Timberlake LecturePLUS 2000


Electron configuration

Electron Configuration

  • 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

    1s22s22p6

    main shell subshell

Timberlake LecturePLUS 2000


Order of filling

Order of Filling

  • 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


Writing electron configurations

Writing Electron Configurations

H1s1

He 1s2

Li 1s22s1

C1s22s22p2

S1s22s22p63s23p4

Timberlake LecturePLUS 2000


Sublevel blocks

Sublevel Blocks

s1 s2 p1 p2 p3 p4 p5 p6

1

2

3d1 - d10

4

5

6

f1 - f14

Timberlake LecturePLUS 2000


Periodic table and electron configuration

Periodic Table and Electron Configuration

  • 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


Learning check s2

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.1s22s22p63s11 or 2

B. 1s22s22p63s23p61 or 2

C.1s22s22p63s23p64s11 or 2

D. 1s22p83s11 or 2

E.1s22s22p63s23p71 or 2

Timberlake LecturePLUS 2000


Solution e2

Solution E2

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

A. 2, 2, 8, 52

B. 2, 8, 3 2

C. 2, 8, 51

D. 2, 6, 7 2

Timberlake LecturePLUS 2000


Learning check s3

Learning Check S3

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

A. Cl

B. Sr

C. I

Timberlake LecturePLUS 2000


Solution s3

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

Timberlake LecturePLUS 2000


Learning check s4

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

Timberlake LecturePLUS 2000


Solution s4

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

Timberlake LecturePLUS 2000


Orbital

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.

Timberlake LecturePLUS 2000


S orbitals

s orbitals

3s

2s

1s

Timberlake LecturePLUS 2000


Three p orbitals

Three p Orbitals

px

pz

py

Timberlake LecturePLUS 2000


P subshell contains p orbitals

p subshell contains p orbitals

Timberlake LecturePLUS 2000


D orbitals

d orbitals

Timberlake LecturePLUS 2000


Learning check s5

Learning Check S5

A. Number of electrons in a p orbital

1) 1e2) 1e or 2e3) 3e

B. Number of orbitals in a p subshell

1) 12) 23) 3

C. Number of orbitals in 4d subshell

1) 12) 33) 5

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

1) 2e2) 5e3) 10e

Timberlake LecturePLUS 2000


Solution s5

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


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