<a href="https://en.wikipedia.org/wiki/Skeletal_formula" class="extiw" title="w:Skeletal formula">Skeletal formula</a> of ammonium
<a href="//commons.wikimedia.org/wiki/User:Leyo" title="User:Leyo">Leyo</a>
<span class="int-own-work" lang="en">Own work</span>