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# How to write chemical formulae

### Simple chemical notation
For simple chemical notation, you can using the via the `x^2y` button in the toolbar. All details [here](https://support.authorea.com/en-us/article/how-to-write-mathematical-equations-and-formulae-9r2qad/?1588289166413).

### More complex chemical notation
Go to your article's Data folder from the toolbar and add a file called header.tex  with the following line in it:

```\newcommand*\chem[1]{\ensuremath{\mathrm{#1}}}```
Then, go back to the article view, insert a LaTeX snippet and type some chemical formulae, for example:
```$\chem{H_2} + (1/2)\,\chem{O_2} = \chem{H_2O}$```
 will produce:
![](https://storage.crisp.chat/users/helpdesk/website/d38f777e-0276-4c52-8a15-b5855ac4903c/4f0f166b-bd1d-4d1e-9629-e3e20eebcac2.png)
```\({}^{4}_{12}\mathbf{C}^{5+}_{2}\)```
will produce:

![](https://storage.crisp.chat/users/helpdesk/website/d38f777e-0276-4c52-8a15-b5855ac4903c/f9b0078a-dcdf-40c9-b928-4ba0a0a50ea3.png)