As you go across the periodic table, do atoms get bigger or smaller? why?

Smaller - more valence electrons as you go across the period, so more electrons are being pulled closer towards the nucleus

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.