What determines that an element is a metal?
There are many ways to identify a metal
A metal generally has 1,2 or 3 valence electrons in its outermost shell
A metal is generally lustrous, hard, malleable, ductile, and solid. It is a good conductor of heat and electricity.
Metals are generally very good reducing agents as they have a high tendency to lose electrons.Their electronegativity is very low.Metals also form cations which are smaller than original atom.They mostly form ionic bonds although there are certain metals such as aluminium, iron, lithium and beryllium who form covalent bonds.
Metals generally react easily with acids and bases both although metals such as lead, gold, platinum, copper etc are non reactive.