Quantum numbers allow a new model to explain the emission spectra of elements with more than 1 electron. There are 4 quantum numbers: n, l, ml and ms. The first 3 numbers describe the orbitals and the last one describes the number of electrons that can be in the orbital.
Principal Quantum Number (n)
– Describes the main energy level and size of the orbital
– The larger n is, the larger the orbital
– Thus, the greater the probability to find an electron further from the nucleus
Restrictions: n = 1, 2, 3, …, ∞
Secondary (Angular) Quantum Number (l)
– Describes the shape of the orbital
– Divides shells into smaller groups of orbitals called subshells or sublevels, that are identified by a letter
|
l |
Letter |
|
0 |
s |
|
1 |
p |
|
2 |
d |
|
3 |
f |
|
… |
… |
– As l increases, the energy of the subshell increases (s<p<d<f)
Restrictions: l = 0, …, n-1
Magnetic Quantum Number (ml)
– Describes the orientation in space of the orbital
Restrictions: ml = –l, …, 0, …, +l
Spin Quantum Number (ms)
– Describes the orientation of spin of the electron on its axis
– 2 electrons can spin in one orbital, one spins one way, the other spins the opposite way
Restrictions: ms = +½ or -½.
This article was written for you by Samantha, one of the tutors with SchoolTutoring Academy.