How do you find the oxidation of PCl3?

Question

Alright, so today, I've been learning about oxidation numbers.

I find that they are very much like naming binary compounds etc.
However, in this molecular compound, I don't see how you can make it balance out with oxidation numbers. I mean, Chlorine needs to gain 1 electron to have a full outer energy level, and Phosphorus needs 3. Also, there aren't any rules that specify like fluorine what one of the oxidation numbers must be. I am quite stumped. If any background and explanation about this topic, and this question could be provided, thanks!

Answer 1

PCl3: Cl is -1, so P is +3

The important thing to remember about oxidation numbers is that they have no physical meaning. Sometimes oxidation numbers are numerically equal to valence, but that's just a coincidence. Oxidation numbers are a system of bookkeeping whose only use is to balance redox equations.