How the metallic and non-metallic properties of chemical elements change: a) in periods; b) in groups?

a) in periods; With an increase in the number of electrons at the external energy level of atoms, the metallic properties of chemical elements weaken, and the non-metallic properties increase.
b) in groups; With an increase in the radius of atoms, the metallic properties of chemical elements increase, and non-metallic properties weaken.

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