Mortal sins are those that must be confessed or you're screwed. If you die with some venal sins on the books you might still be ok, but not mortal.

According to Catholics, all sins can be absolved through confession, repentance, and penance. Suicide is a problem because you don't have the opportunity to do this, that's why they say all suicides go to hell.

The list of mortal sins is kind of funny (not ha ha funny). It's mostly boring stuff like not going to mass or sex outside of marriage but then murder is just mixed in with those. And like the commandments, rape is not explicitly mentioned.