**quantum numbers**, to describe the orbitals in which electrons can be found. (SSO: Size, Shape, Orientation)

The

**principal quantum number**(

*n*) describes the size of the orbital.

The

**angular quantum number**(

*l*) describes the shape of the orbital.

The

**magnetic quantum number**(

*m*) describes the orientation in space of a particular orbital.

Orbitals have shapes that are best described as spherical (

*l*= 0), polar (

*l*= 1), or

**cloverleaf**(

*l*= 2). They can even take on more complex shapes as the value of the angular quantum number becomes larger.

(

*n*) cannot be zero. The allowed values of

*n*are therefore 1, 2, 3, 4, and so on

(

*l*) can be any integer between 0 and

*n*- 1. If

*n*= 3, for example,

*l*can be either 0, 1, or 2.

(

*m*) can be any integer between -

*l*and +

*l*. If

*l*= 2,

*m*can be either -2, -1, 0, +1, or +2.