How many orbitals are found in the d sublevel?

1 Answer
Dec 3, 2015

We can derive this from knowing that the atomic orbitals each exist in accordance with angular momentum quantum number ll.

Recall how ll tells you the shape of the atomic orbital. That just means:

l = 0 -> sl=0s orbital
l = 1 -> pl=1p orbital
l = 2 -> dl=2d orbital
etc.

Additionally, what we have associated with ll is the magnetic quantum number m_lml, the projection of ll in the negative, unsigned, and positive directions. In other words...

m_l = 0, pm 1, pm 2, . . . pm (l-1), pm lml=0,±1,±2,...±(l1),±l

If l = 2l=2, then:

color(blue)(m_l = -2, -1, 0, +1, +2)ml=2,1,0,+1,+2

Each individual m_lml value corresponds to a unique orbital.

That indicates that five orbitals are available in the dd orbitals. Specifically, the d_(z^2)dz2, d_(x^2 - y^2)dx2y2, d_(xy)dxy, d_(xz)dxz, and d_(yz)dyz orbitals.

Furthermore, from knowing that the spin quantum number m_sms for an electron is pm"1/2"±1/2 (two spin states), and recalling the Pauli exclusion principle (two electrons in one orbital must be opposite spins), there can be a max of two electrons per orbital.

Therefore, the total number of electrons in five orbitals can be a maximum of 10.