How many electrons can fill each orbital?

Atomic orbitals

To be able to understand the atomic orbitals you need to look at the table below to see the relation between quantum numbers and atomic orbitals.

n	l	ml	Number of orbitals	Atomic orbital designations	Number of electrons filling orbital
1	0	0	1	1s	2
2	0 1	0 -1, 0, 1	1 3	2s 2px, 2py, 2pz	2 6
3	0 1 2	0 -1, 0, 1 -2, -1, 0, 1, 2	1 3 5	3s 3px, 3py, 3pz 3dxy, 3dyz, 3dxz, 3dx2-y2, 3dz2	2 6 10

From the above table you can see that when l=0, (2l +1)=1 and there is only one value of m_l, thus we have an s orbital. When l= 1, (2l+1)=3, so there are three values of m_l or three p orbitals, labeled p_x , p_y , and p_z .

1- “s” orbital:

- In “s” orbital the probability of finding electron around nucleus is a sphere like shape. (the electron density around nucleus looks like a sphere).

2- “p” orbital:

- The electron density of p orbital looks like a two loop shape.

- If n=2 this means l= 1 and m_l  =-1, 0, 1 so we have three p orbitals that have same shape, size and energy only differ in their orientation.

- “p” consists of three orbitals p_x, p_y and p_z.

3- “d” orbital:

- For l = 2 the m_l  value will be -2, -1, 0, 1, 2 means five; (d_xy, d_yz, d_xz, d_x²_-y² and d_z²).

- “d” contains 5orbitals that is why it can be filled with 10 electrons.

4- “f” orbitals:

There are 7 f orbitals each can be filled with 2 electrons that is why f orbitals can be filled with        14 electrons.