The designation of the orbital "location" of
an electron requires four quantum numbers:
1. Principal quantum number, n,
identifies the main energy level. It has whole numbers, n = 1, 2,
3, 4 ..... As n increases the electrons are generally further from
the nucleus and have total energy.
Values of n range from 1 to 7 in the unexcited
states of the known elements. Values of 1 to infinity are possible in the
excited states of atoms (infinity corresponds to the complete removal of
an electron to form an ion).
2. Subshell quantum number, l ,
identifies sublevels of energy within the main energy level where l
= n - 1 which correspond to l = 0, 1, 2, 3, ..... 6 given
the notation s, p, d, f, g, h
and i.
Each type of subshell has a characteristic shape.
Generally, transitions between subshells increase from s, to p,
to d, to f etc. orbitals.
| n = | l =0,. . .,(n - 1) |
| 1 | 0 (s) |
| 2 | 0,1 (s,p) |
| 3 | 0,1,2 (s,p,d) |
| 4 | 0,1,2,3 (s,p,d,f) |
3. Orbital quantum number, ml , which pins down the location of individual electrons in orbitals, where ml= -l to +l. It defines the number of orbitals in each subshell. For this reason there are one s orbital, three p orbitals, five d orbitals and seven f orbitals.
| l = | ml= -l to +l |
| 0 (s) |
0 One s-orbital |
| 1 (p) |
+1,0,-1 Three p-orbitals |
| 2 (d) |
+2,+1,0,-1,-2 Five d-orbitals |
| 3 (f) |
+3,+2,+1,0,-1,-2,-3 Seven f-orbitals |
4. Spin quantum number, ms, is needed because an electron can occupy the orbital in two different orientations, ms = +½ or -½. The electron can be considered to be spinning around its axis, pointing either up (+½) or down (-½).
In atomic orbital notation, the orbital is designated by:
|
n |
l | ||
|
/ |
\ | ||
| Principal quantum number | Subshell quantum number |
Information provided by: http://www.bpx.cov.ac.uk