Quantum Numbers

1
Chapter 5

• Quantum Numbers
• Part 1

2
Quantum Numbers

• There are four quantum numbers that describe the
  properties of an electron and the orbital that
  it occupies within an atom.

Apple
3
What are orbitals?

• The main division of energy for an electron
  within an atom is called the energy level or
  shell.
• The energy level (shell) is subdivided into
  distinct areas called sublevels (subshells).
• The sublevels are divided into orbitals. The
  orbitals are where the electrons are found.
• Each orbital can hold no more than a pair of
  electrons.

4
Four Quantum Numbers describe the following

• distance from the nucleus
• shape of the orbital
• 3-dimensional positioning of the orbital
• direction of electrons spin within the orbital

5
The First Quantum Number The Principal Quantum
Number

• Abbreviated as n
• n 1,2,3...
• Represents the distance of an electron from the
  nucleus the main energy level of the electron.

6
What else does the Principal Quantum Number (n)
tell us?

• n number of sublevels in the energy level.

7
What else does the Principal Quantum Number (n)
tell us?

• n2 number of orbitals in the energy level.

8
What else does the Principal Quantum Number (n)
tell us?

• 2n2 maximum number of electrons possible in the
  energy level.

9
(No Transcript)
10
The Second Quantum Number (Types of Sublevels)

• The second quantum number identifies the type of
  sublevel that the electron occupies.
• There are four types of sublevels in atoms.
• The sublevels are identified by the letters
  s, p, d, f

11
s sublevel and p sublevel
p orbitals have a dumbbell shape
s orbitals have a spherical shape
a
12
Types of sublevels

• There are four types of sublevels in atoms.
• The sublevels are designated s, p, d, f.

13
The Third Quantum Number

• The third quantum number identifies the orbital
  that the electron is in.
• An orbital is an area within a sublevel that can
  hold up to two electrons.

14
An s sublevel has one orbital

15
A p sublevel has three orbitals

16
A d sublevel has five orbitals

17
An f sublevel has seven orbitals

18
The 4th Energy Level

• n ?

19
The 4th Energy Level

• n 4

20
The 4th Energy Level

• How many sublevels are present and what type are
  they?
• Four sublevels s, p, d, f

21
The 4th Energy Level

• How many orbitals are present?
• n2 (4)2 16

22
The 4th Energy Level

• What is the maximum number of electrons?
• 2n2 2(4)2 32

23
The Fourth Quantum Number s

• Also called the spin quantum number.
• Can be either 1/2 or -1/2.
• Specifies the direction of spin of the electron
  on its axis.
• Spins are designated up or down.

24
Electron Spin

• Opposite spins produce opposite magnetic fields.

1/2
-1/2
25
What sublevel is the first to be filled with
electrons?
O
26
Which sublevel listed contains orbitals of the
highest energy?
O
27
Finish Video

• Electron Arrangement and Bonding.

28
Homework

• Complete Chapter 5 Worksheet 1