Periods and Groups of Elements, Metals, Nonmetals and Metalloids Period 1---2 elements Period 2---8 elements Period 3---8 elements Period 4--18 elements Period 5--18 elements Periods-A single horizontal row Period 6--32 elements Period 7--32 elements Metalloids include: B, Si, Ge, As, Sb, Te, Po, and At. They are semiconductors; They are sometimes used as insulators of electric wires. Metals are shiny solids. They are good conductors of electricity and heat. All metals are solid except mercury, Hg, which is a liquid Groups- A single vertical column of elements Group 1A-8ARepresentative Elements Group3B-8B-Transitional Elements Group 1A-Alkali metals-very reactive Group2A-Alkalline earth metals- less reactive. Group 7A- Halogens-F, Cl, Br, I Group 8A-Noble gases- He, Ne, A Metals are the elements to the left of the zigzag line, except hydrogen. Nonmetals are the elements to the right of the zigzag line. Metalloids are the elements located on the zigzag line.. They are of electricity.