an ion is an atom missing or having an extra electron from its orbital shell. an atom is made of a proton(+) and a nuetron(nuetral)as its nucleus. surrounded by orbitl shell up to 7 shells. the 7th being most dense like you. on these shells eletrons(-) move within the layer of each shell. held together by electromagnetics. neg to pos. right? electrons have no mass. where each element is mesured by its atomic weight proton+nuetron= amu. number of electrons on shell is 2(N)squared. a 1/2jawbreaker is a great model of a atom. all the dots are electrons! layers orbital shells and of course the nucleus the center.