Claartje fietst nooit in haar onderbroek, Pietje soms.

Claartje= Cl2 = Chloor.
Fietst = F2 = Fluor.
Nooit = N2 = Stikstof.
In = I2 = Jood.
Haar = H2 = Waterstof.
Onder= O2 = Zuurstof.
Broek = BR2 = Broom.
Pietje = P4 = Fosfor.
Soms = S8 = Zwavel.