Chem! why do we use roman numerals (aka stock system) when you write the name for a compound with (example: ) tin in it even though it’s a main group metal?

Roman numerals are used in naming ionic compounds when the metal cation forms more than one ion. The metals that form more than one ion are the transition metals, although not all of them do this.

SnBr2 - Tin(II) Bromide

"the periodic table is arranged in order of atomic number."

a polar bond is formed when electrons are shared unevenly between atoms