Zu vs zum

I understand that “zum” is a contraction of “zu dem”. Is it in a sentence okay to write both “zu dem” and “zum” or would one of them be considered less formal?
 

I don't think anyone would ever use zu dem.

Hallo RexV and sfpugh!

This is a good question, and it's actually a little more complicated than just always making it zum.

Basically, if we're talking about a phrase where dem is acting as a regular article and zu dem comes before a noun (e.g. Ich gehe zum Schloss "I am going to the palace"), then zu dem is contracted to zum. If, however, we're talking about a more complex phrase where dem is acting as a pronoun (e.g.  Der Mann, zu dem das Schloss gehört "The man to whom the palace belongs"), then it can't be contracted to zum and it must remain zu dem. 

I hope that this clears everything up!

Bis später,

Liss

That's interesting, I hadn't thought about that possibility. Thanks.

Bitte! :) Viel Spaß!