I know that it's because of their different atomic structure, but why? I think I have an idea of why specific properties are present in some elements, like radioactivity(because of their instability) or reactivity with other elements(because of their electron configuration) or atomic weight (because of the number of protons and neutrons)...etc. But how do any of those(or something else I'm most likely unaware of) explain color, texture, melting points and boiling points, density, and many other properties I can't think of at the moment(what are the other properties?). Like, why is gold's color different than silver?
I don't know much about science, besides a few things I read here and there. What field of science would answer these questions? I figured it would be chemistry, but would physics give a more basic answer, as it underlines chemistry?
Also, how many years would it take me to have a firm understanding of physics? I'm thinking of starting out soon. How would you suggest I begin? I didn't think I was smart enough so I haven't bothered up until now. How hard is it going to be?