Write the metals and nonmetals and metalloids in the first 30 elements

Metals: Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn

Non-metals: H, He, C, N, O, F, Ne, Si, P, S, Cl, Ar

Metalloid: B

Explanation: The first 30 elements are H, He, Li, Be, B, C, N, O, F, Ne, Na,

Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn

Metallic elements are more electropositive (tending to form ions by donating electrons) with fewer electrons in their outer shell

Non-metallic elements are more electronegative (tending to form ions by accepting electrons) with more electrons in their outer shell

Metalloids are elements somewhere between, but without any specific clear boundary between them and metals/non-metals

group1 and group2 elements, with one or two outer electrons, are all metals: Li, Na, K, Be, Mg, Ca

similarly the transition metals 21-30 are all electropositive and metals.

The noble gases He, Ne, Ar are gases that have completed outer shells and are non-metallic, likewise the halogens F, Cl with 7 outer electrons, and  O and S with 6 are non-metals. N and P (5 outer electrons) are non-metallic as are C and Si (4 outer electrons).

This leaves H, B, Al. H, with its single electron close to the nucleus is a non- metallic gas. Al (3 outer electrons) is metallic, but B, has its 3 electrons close to the nucleus and has the in-between character of a metalloid.