So I'm looking at some Kanji sheets for the first time, just trying to get a feel for how difficult they're going to be when I actually do attempt to memorize them. Ichi lists a kunyomi of ひと*つ and another source has this, similarly: ひと・つ
What I'd like to know is why can't these be written like ひとつwithout that little spacer? Is there a difference in pronunciation or is it just one of those "that's just the way it is" scenarios?