Does silicon form a cation or is it anion?

Silicon generally forms at least polar covalent bonds, like carbon, as befits its status as a Gropu 4A nonmetal. The only obvious exception I can think of is SiC, which despite the similarity you might expect to graphite or diamond does, I think, have significant ionic or metallic character to its bonding in the solid state.

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates