1.Metals are on the left side of the zigzag line
Nonmetals are on the right side
mettaliods compose the zigzag line (B,Si,Ge,As,Sb,Te,Po)
Noble gasses are the last column on the periodic table
2. The exponent of the highest energy level
3. metals have the lowest valence electrons, nonmetals have the 2nd to the highest, and noble gases have the highest.
4. metals (1-3)