J.W. Dobereiner formed the Law of Triads: A link between the atomic weight and distinct elements in groups of threes

J.A.R. Newlands formed the Law of Octaves: The properties in every 8th element were similar; E.g.: F, Cl.

Mendeleev formed The Periodic Law: When elements were arranged in order of atomic mass, repeated properties were found

Moseley formed the Modern Periodic Law: When elements were placed in atomic number, there were patterns of properties

Inductive Reasoning: Definite measurements and observations lead to the acknowledgement of patterns, which can lead to a hypothesis and later a theory

Deductive Reasoning: Start at a theory and test the theory

Group 1 - Alkali Metals

Group 2 - Alkaline Earth Metals

Group 15 - Pnictogens

Group 16 - Chalcogens

Group 17 - Halogens

Group 18 - Noble Gases

Metals are good conductors of heat and electricity, malleable, ductile, and lustre

Nonmetals are poor conductors

Nonmetals gain electrons(reduced), Metals lose electrons(oxidized)

Metalloids: Ba, Si, Ge, As, Sb, Te, At

Some metalloids are semiconductors because of their intermediate, highly temperature-dependent electrical conductivity e.g. SI, Ge