These metals are situated between the transition metals and the non-metals. Aluminium is often considered a member of the S-block division, where its properties make its presence more fitting. Zinc, cadmium and mercury are sometimes classified as transition metals, and sometimes not. It should be remembered that there are few absolute rules in connection with the periodic table, and that some elements are particularly resistant to easy classification.
In comparison with the transition metals, these metals possess relatively low melting and boiling points. A comparison of the melting points of copper, zinc and gallium, for example, shows the figures fallling from 1084.87 degrees Celsius to 419.58 degrees Celsius to 29.77 degrees Celsius, as we move from the transition metals to the other metals. Gallium, in fact, will melt in the hand.
Gallium and germanium, situated immediately to the left of the staggered line that divides the metals from the non-metals, are in fact metalloids, which means that they possess properties considered both typically metallic and typically non-metallic. Accordingly, they are characterized by their semiconductor properties, which fall midway between those of an insulator and those of a conductor.
These metals are markedly less reactive than the alkali metals and the alkaline earth metals. They combine less readily with non-metallic elements such as oxygen and chlorine.
