# Definition of Sublevel

A sublevel is an electron orbital. Sublevels are designated s, p, d or f.

These sublevels or orbitals have characteristic shapes which can be used to explain and predict the chemical bonds that atoms can form.

## s, p, d, and f sublevels

s sublevels are spherically shaped. The p, d and f sublevels have more complex shapes.

s orbitals can hold a maximum of 2 electrons, p a maximum of 6 electron, d a maximum of 10 electrons, and f a maximum of 14 electrons.

The sublevel occupied by any electron is determined by the electron's angular momentum quantum number, l. It is found by solving the Schrodinger equation, allowing us to find probability distributions for an electron in an atom.

For example, we can say that an electron in a hydrogen atom's 1s sublevel will be found 99 percent of the time somewhere in a sphere with a given radius around the nucleus. This is the reason we can draw the s sublevel as a sphere.

Sublevels can also mix with one another to produce new, hybridized orbitals.

An s sublevel

The p, d and f sublevels are also drawn on the basis of where an atom's electrons are most likely to be found.

A p sublevel

### Sublevel schematics: the 2s and 2p sublevels

Examples of the sublevels found in various atoms are shown below. The superscript shows the number of electrons in each sublevel.

Hydrogen: 1s1

Carbon: 1s2 2s2 2p2

Chlorine: 1s2 2s2 2p6 3s2 3p5

Argon: 1s2 2s2 2p6 3s2 3p6

In general, electrons go into the lowest available energy sublevel. The general order in which sublevels are filled is:

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

Given this, we can answer questions like: "what are potassium's electron sublevels?"

Potassium has 19 electrons, and we know that s orbitals hold a maximum of two electrons and p a maximum of six. Potassium's electron sublevels will be:

1s2 2s2 2p6 3s2 3p6 4s1

For some individual atoms, there may be exceptions to this filling order, as discussed in the comments section for iodine.

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