1. Chapter 5
Quantum Numbers

2. Quantum Numbers
There are four quantum numbers that describe the properties of an electron and the “orbital” that it occupies within an atom.
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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:
Energy level (distance from the nucleus)
Sublevel (shape of the orbital)
Orbital (3-dimensional positioning)
Direction of the electron’s 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.

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
s orbitals have a spherical shape
p orbitals have a dumbbell 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?

23. The Fourth Quantum Number
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?

26. Which sublevel listed contains orbitals of the highest energy?

27. Homework
Complete Chapter 5 Worksheet 1