an atom has electrons in 3 energy levels. in the Bohr model of an atom, the number of core electrons is the number of elevtrons in energy levels

10 years is the answer

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.