Question

what similarity defines a group of elements on the periodic table?
a) electron structures
b) melting point
c) densities
d) numbers of electrons

Explanation:

Elements in the same group of the periodic table have similar electron structures, especially the same number of valence electrons. This similarity in electron structure leads to similar chemical properties. Melting point, density, and number of electrons (in total) can vary within a group.

Answer:

A. electron structures