Which is another name for groups of elements? actinides families halogens periods

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

If it is an isoelectronic series select true, if not select false. o2-, s2-, se2-, te2- na+, k+, rb+, cs+ n3-, p3-, as3-, sb3- ag, cd+, sn3+, sb4+ f-, cl-, br-, i- f-, ne, na+, mg2+ s2-, s, s6+