Formula to pull a first name

I don't know if this is possible, but it will save a lot of time if it is. I have a donor database where each donor is known by their full name, ie. "Kate Jacobs". Is there any way that I can add a column with some sort of formula that could just pull the first word from that record? For the purpose of mail merge - I want to be able to do a FName tag, but currently will have to manually go through and rename all the contacts.