Hi Chrisell,
-chen is a diminutive ending in
German and it works for girls (
Gretchen, Lieschen, Lenchen) and boys (Hänschen, Kläuschen), but the name
Jochen does not belong to that group. Here, the -chen-ending sounds different. It's just a short form of
Joachim.
By the way - Mädchen isn't used as a given name in Germany at all. It's just a vocabulary word for "girl".
/
Satu
http://www.nordicnames.de/