## Atomic Orbitals Definition

Orbit is the definite path of an electron that moves around the nucleus in an atom. This is similar to a planet, moves around the sun. Orbitals are the space or region around the nucleus where the electron are calculated to be present. So orbits and orbitals have totally different meanings.

## Shapes of orbitals

Different shapes of orbitals are drawn depending on the possibility of finding electrons around the nucleus. These are s, p, d and f. The shapes of these orbitals are discussed below:

### s-orbitals

The s-orbitals are solid spherical shape around the nucleus. When principal quantum number n = 1 and azimuthal quantum number l = 0, that is 1s orbital which is closest to the nucleus. When n = 2 and l = 0 , i.e 2s orbital which contains one node. When n = 3 and l = 0, i.e 3s orbital which contains two nodes. The pictorial representation of these orbitals are shown below:

So we can say that the s orbitals are always spherical regardless of the principal quantum number, regardless of size, regardless of the number of nodes they contain.

### p-orbitals

The p-orbitals are dumb-bell shape contains two lobes just like two identical balloons tied together. The two lobes stay away from each other along the axial line. When n = 1, there are no p-orbitals, it has only s-orbital. When n = 2 and l = 1, the magnetic quantum number m = +1, 0, -1. Thus three dumb-bell shape p-orbitals are found pointing towards the three axes x, y and z which are perpendicular to each other. These three orbitals are named as p_{x}, p_{y} and p_{z}. The nodal plane is the plane where there are no possibility of finding any electrons. The nodal planes of p_{x}, p_{y}, p_{z} are yz, xz and xy respectively.

#### d-orbitals

The d-orbitals have different shapes and these are only available when principal quantum number n = 3 or more. When n = 3, l = 2, then m = +2, +1, 0, +1 and +2. That means five d-orbitals are available in an atom. The directions, names and the shapes of these orbitals are as follows:

### f-orbitals

The f-orbitals also have different shapes and these are only available when principal quantum number n = 4 or more. When n = 4, l = 3, then m = +3, +2, +1, 0, +1, +2 and +3. That means seven d-orbitals are available in an atom. The directions, names and the shapes of these orbitals are as follows:

## Electron distribution in orbitals

### s-orbitals

Number of maximum electrons that each s-orbital can hold is two regardless of the number of principal quantum number (n). Such as 1s^{2}, 2s^{2}, 3s^{2} etc. We need to recall that the spin of these two electrons must be opposite.

### p-orbitals

Each p-orbital can posses maximum of two electrons each that means six for all three p-orbitals. We can write that either 2p^{6} or 2p_{x}^{2} 2p_{y}^{2} 2p_{z}^{2}. The spin of each of these orbitals must be opposite.

### d and f-orbitals

The total number of electrons in d-orbitals and f-orbitals are ten and fourteen respectively. Here maximum two electrons can occupy in each of these d or f-orbitals.

### Spin quantum number

Spin of these two electrons in each orbitals will be always in opposite direction. Following image shows the maximum electron distribution in each orbitals: