Chem04 Quantum Shells, Subshells, Orbitals

Chem04 Quantum Shells, Subshells, Orbitals

by Nicholas Hendley

​Loosely adapted from Chemistry: Concepts and Problems

​Quantum Numbers define the Electron

​Every electron is defined by FOUR quantum numbers.

• ​The Principal Quantum number (n) describes the energy level (shell).

• ​ ​The Angular Momentum (or Azimuthal) Quantum number (l) describes the energy sublevel (subshell).​ [Sometimes, this is called the orbital shape, but it is a sublevel.]

• The Magnetic Quantum number (m_l) describes the orbital (orientation).​

• The Spin Quantum number (m_s) describes the electron.

Multiple Choice

Which quantum number defines the energy level?

• Principal

• Angular Momentum

• Magnetic

• Spin

​The Principal Quantum Number (n)

​Corresponds to the energy level (or energy shell).

​Possible values of n = 1, 2, 3, 4, 5, 6, 7

​The lowest energy is n = 1.

​The highest energy is n = 7.

​

Multiple Choice

The lowest energy level is n = 0.

• True

• False

​The Angular Momentum Quantum number (l)

​Corresponds to the energy sublevel (or energy subshell).

​Possible values of l = 0 up to n - 1

​This defines the shape of the orbitals.

​Four Sublevel Shapes

​l = 0 = s

"sphere"

​​l = 1 = p

"peanut" or "dumbbell"

​​l = 2 = d

"double dumbbell"

​​l = 3 = f

"flower"

​Assigning Electrons

• ​Imagine this is like an apartment building.

• ​The first energy level (n = 1), can only support an s sublevel.

• ​The second energy level (n = 2), can support only 2 sublevels: s and p.

• ​The third energy level (n = 3), can support only 3 sublevels: s, p and d.

• ​The fourth energy level (n = 4), can support all 4 sublevel types: s, p, d and f.

​Naming sublevels

Naming the sublevels by using the energy level, then the sublevel shape.​

• ​So, the s sublevel on n = 1 would be called 1s.

• ​​Next would be the s sublevel on n = 2 would be called 2s.

• ​The p sublevel on n = 2 would be called 2p.

• And so forth.

Multiple Choice

What would you call the sublevel where n = 3 and l = 2?

• 2p

• 3s

• 3p

• 3d

Multiple Choice

If you're dealing with electrons in the 3p sublevel, what do you know is true?

• n = 2

• n = 1

• l = 2

• l = 1

Multiple Choice

Which of the following does not exist?

• 1s

• 1p

• 2s

• 2p

​Magnetic Quantum Number (m_l)

​​Corresponds to the orbital.

​Possible values range from -l to +l, including 0

Each orbital can only hold 2 electrons

​Orbitals per sublevel

​An s (l = 0) sublevel has 1 orbital

(m_l = 0)

​​A p (l = 1) sublevel has 3 orbitals

(m_l = -1, 0, +1)

​​A d (l = 2) sublevel has 5 orbitals

(m_l = -2, -1, 0, +1, +2)

​​An f (l = 3) sublevel has 7 orbitals

(m_l = -3, -2, -1, 0, +1, +2, +3)

​

​In the apartment analogy, these are like the rooms of the apartments.

Multiple Choice

How many subshells are there in the second shell?

• 1

• 2

• 3

• 4

Multiple Choice

How many orbitals are in the second shell?

• 1

• 2

• 3

• 4

​The Spin Quantum Number (m_s)

​​​Corresponds to the electron.

​Possible values are either +½ or -½

Each orbital can only hold 2 electrons

​Electrons must have opposite spins within the same orbital

Multiple Choice

How many electrons can occupy the second shell?

• 1

• 2

• 4

• 8

Multiple Choice

Which subshell fills first in the third energy level?

• d

• p

• s

• f

Multiple Choice

Which subshell is not found in the third energy level?

• d

• p

• s

• f

Multiple Choice

How many subshells are in the third energy level?

• 1

• 3

• 5

• 7

Multiple Choice

How many orbitals are in the third energy level?

• 1

• 3

• 4

• 9

Multiple Choice

How many electrons can fit in the third energy level?

• 2

• 32

• 8

• 18

Multiple Choice

How many electrons fit in the 4d subshell?

• 2

• 6

• 10

• 14

Multiple Choice

How many electrons fit in the 5d subshell?

• 2

• 6

• 10

• 14