that google likes to keep quiet

for their services, you must enter a first and second name. if you try to leave your second name blank, they don't let you.
however, for business and the like they actually have a feature where if you fill in the last name slot with a period, it removes the 2nd name entirely. if you do this with a personal account, they give you a warning telling you that it's not recommended, but you can do it anyway

you can go ahead and file this under "who cares" if you want but i for one am glad to finally know this and wish i had found out sooner