Valence

Name:
Valence
Detailed information:
A whole number that represents or denotes the combining power of one element with another. By balancing these integral valence numbers in a given compound, the relative proportions of the elements present can be accounted for. If hydrogen and chlorine both have a valence of 1, oxygen a valence of 2, and nitrogen 3, the valence-balancing principle gives the formulas HCl, H₂, NH₃, Cl₂O, NCl₃, and N₂O₃, which indicate the relative numbers of atoms of these elements in compounds that they form with each other. In inorganic compounds it is necessary to assign either a positive or negative value to each valence number, so that valence balancing will give a zero sum by algebraic addition. Negative numbers are called polar valence numbers (–1 and –2). The valence of chlorine may be −1, +1, +3, +5, or +7, depending on the type of compound in which it occurs. In organic chemistry only nonpolar valence numbers are used.See Bond, Chemical; Oxidation; Oxidation Number; Coordination Number.