Equivalent weight is the atomic weight of an element or radical divided by the valence it assumes in a chemical compound. ... A chemical element, often called simply element, is a substance that cannot be divided or changed into different substances by ordinary chemical methods. ... The term radical can have two distinct meanings in chemistry. ... Valence is a scientific term in chemistry to describe electrons in the outermost orbital. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ...

For example, hydrogen, with atomic weight 1.008 and valence 1, has an equivalent weight of 1.008. Oxygen assumes a valence of 2 and has an atomic weight of 15.9994, so it has an equivalent weight of 7.9997. General Name, Symbol, Number Hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1, s Density, Hardness 0. ... General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ...

Elements may assume different equivalent weights in different compounds. For example, iron (atomic weight 55.845) assumes equivalent weight 27.9225 if it is valence 2 in the compound (ferrous); or 18.615 if it is valence 3 (ferric). General Name, Symbol, Number iron, Fe, 26 Chemical series transition metal Group, Period, Block 8 (VIIIB), 4, d Density, Hardness 7874 kg/m3, 4. ...

The equivalent weight can also be computed for other than pure elements. For example, the carbonate radical (CO₃) has a formula (atomic) weight of 76.0083 and assumes valence 2 in compounds, so its equivalent weight is 38.00415. Carbonate is an anion with a charge of -2 and an empirical formula of CO32-. An aqueous solution of carbon dioxide contains a minute amount of H2CO3, called carbonic acid, which dissociates to form hydrogen ions and carbonate ions. ...