This maybe a general science question but I'll put it here. When we say that an element has so-and-so properties, how do we know those are the only properties it has. For example:- We say an element has properties like electron affinity, electro-negativity etc. How do we know these are the only properties. There could be more, right? Well, I have an answer and a question to this. Answer is that, we don't know. Only by experimenting and looking at new phenomena we come to know of new properties. My question is, lets say if we know all the laws of physics perfectly. Since we know an element is made of electrons, protons and neutrons, could we then at least theoretically calculate all the properties? I don't know why but this question is killing me. I can't sleep!