MELTING AND BOILING POINTS
Both melting and boiling points show some periodicity but observable
regularities are largely confined to the groups. In Group O, the
noble gases, the melting and boiling points of the elements are low
but rise down the group; similarly in Group VIIB, the halogens, the
same trend is observed. In contrast the metals of Group IA (and II A)
have relatively high melting and boiling points and these decrease
down the groups. These values are shown in Figure 1.8.