The Transition Elements

The ‘transition’ metals are so called because they interrupt the sedate progression in the periodic table through groups of just eight elements. They are a different type of atom from both the non-metals and the metals of the rest of the periodic table. In the case of the typical¹ elements there is an abrupt change in chemical properties with atomic number, i.e. each additional electron. In the transition elements this sudden change in properties is replaced by a gradual change from metal to metal, reflecting their different type of atomic electronic structure. Naturally, this means that molecules containing the transition metals will exhibit some properties which we have not met so far and the relationship among the properties of these elements will be different from those of the typical elements. It is important to emphasise, however, that, at the moment, there is no coherent qualitative theory of the bonding in transition-metal molecules.