Question

How do you draw electron orbital diagrams?

Answer 1

You use lines for orbitals and arrows for electrons.

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Something simple is `"He"`, whose configuration is `1s^2`. So, you fill one orbital with two electrons, as is the maximum for one `s` orbital.

`1s^2`:

`color(white)([(color(black)(ul(uarr darr))),(color(black)(1s))])`

If you add more orbitals, you include their relative energies. Say you have `"Li"`. Then you have a `2s` orbital at a (significantly) higher energy.

`1s^2 2s^1`:

`color(white)([(color(black)(ul(uarr color(white)(darr)))),(color(black)(2s))])`

`" "`
`" "`

`color(white)([(color(black)(ul(uarr darr))),(color(black)(1s))])`

With `"B"`, you introduce the `2p` orbital, which is even higher in energy than the `2s`. There are also three of them, instead of just one.

`1s^2 2s^2 2p^1`:

`color(white)([(color(black)(ul(uarr color(white)(darr)))),(color(black)(2p_x))]) color(white)([(color(black)(ul(color(white)(darr) color(white)(darr)))),(color(black)(2p_y))]) color(white)([(color(black)(ul(color(white)(darr) color(white)(darr)))),(color(black)(2p_z))])`

`color(white)([(color(black)(ul(uarr darr))),(color(black)(2s))])`

`" "`
`" "`

`color(white)([(color(black)(ul(uarr darr))),(color(black)(1s))])`

Filling up the `2p` orbitals some more, let's look at `"F"`. You add one electron at a time to each `p` orbital to maximize total spin, as per Hund's Rule, and then pair them up afterwards.

`1s^2 2s^2 2p^5`:

`color(white)([(color(black)(ul(uarr darr))),(color(black)(2p_x))]) color(white)([(color(black)(ul(uarr darr))),(color(black)(2p_y))]) color(white)([(color(black)(ul(uarr color(white)(darr)))),(color(black)(2p_z))])`

`color(white)([(color(black)(ul(uarr darr))),(color(black)(2s))])`

`" "`
`" "`

`color(white)([(color(black)(ul(uarr darr))),(color(black)(1s))])`

And that should cover the general idea.