ABSTRACT
The chemistry of an atom is to a large extent determined by its outer electrons because they are the first to get involved in reactions. So the elements Sc to Zn in period 4 are similar in many ways. All the d-block elements are metals with useful properties for engineering and con struction. Most have high melting points. A plot of physical properties against proton number often has two peaks corresponding to the half-filling and then filling of the d-shell. (See figure.)
Some, but not all, of the d-block elements are classified as transition elements.
