2. Set of 4 numbers used to describe the electrons in terms of :
QUANTUM NUMBERS
Set of 4 numbers used to describe the electrons in terms of :
Distance from the nucleus
Shape of the orbitals
Orientation in space
Direction of electron spin

3. PRINCIPAL QUANTUM NUMBER, n
Refers to the main energy levels
Related to the average distance of the electron from the nucleus
Can only have integral values of
n = 1, 2, 3, 4 etc.

4. AZIMUTHAL or SECONDARY QUANTUM NUMBER, l
Defines the shape of the orbital.
Also refers to the energy sublevels
subshell
Azimuthal quantum number, l s p 1 d 2 f 3

5. MAGNETIC QUANTUM NUMBER, ml
Describes the orientation of the orbitals in space.
The range of magnetic quantum numbers defined by the formula ml = 2l + 1 and takes the integer value between –l to +l including 0
subshell
Possible magnetic quantum numbers, m l s p
-1, 0, +1 d
-2, -1, 0, +1, +2 f
-3, -2, -1, 0, +1, +2, +3

6. SPIN QUANTUM NUMBER, ms
- differentiates how two electrons behave under a magnetic field.
Can only have two possible values
+½ and -½

7. Example. What are the possible quantum numbers for the outermost electron of oxygen?
SOLUTION:
Identify the final orbital occupied by the electron.
1s2 2s2 2p4
n =
l =
ml =
ms = 2
2 p4 1
-1, 0, +1
+½ , -½

8. What are the possible quantum numbers for the outermost electron of chromium?
SOLUTION:
Identify the final orbital occupied by the electron.
1s2 2s2 2p6 3s2 3p6 4s1 3d5
n =
l =
ml =
ms = 3
3 d5 2
-2, -1, 0, +1, +2
+½ , -½

9. For each subshells given below, give the maximum number of orbitals and electrons possible
Subshell or sublevel
Number of orbitals
Number of electrons 8s 3p 3d 6f 6s 5d 4f

11. Electron Population Distribution or Electron Orbital Notation
Show the electron population distribution for 15P.
P has 15 electrons.
Its electron configuration is 1s2 2s2 2p6 3s2 3p3.
The electron population distribution for P is: 1s 2s 2p 3s 3p