Periodic Trends in Chemical Properties

An element's single most fundamental chemical property is its COMBINING POWER — its capacity to form chemical bonds — expressed numerically as its VALENCY (or valence): the number of chemical bonds an atom of that element can form when it becomes part of a molecule. A closely related but distinct term is OXIDATION STATE (or oxidation number): unlike valency, which carries no sign, oxidation number is signed (+ or -), with the sign for each bonded atom decided by the relative electronegativities of the two atoms involved in the bond (the more electronegative atom is assigned the negative oxidation state). The second broad chemical property covered in this section is CHEMICAL REACTIVITY — how …