For example, 2 + 3 + 5 = 10 is an equation. Chemistry A written representation of a chemical reaction, in which the symbols and amounts of the reactants are separated from those of the products by an equal sign, arrow, or a set of opposing arrows. For example, Ca(OH) 2 + H 2 SO 4 = CaSO 4 + 2H 2 O, is an equation.
an element is a pure substance that is made from a single type of atom elements are the building blocks for all the rest of the matter in the world examples of elements include iron oxygen hydrogen gold and helium
element. 1  a component or constituent of a whole or one of the parts into which a whole may be resolved by analysis: Bricks and mortar are elements of every masonry wall. 2  Chemistry. one of a class of substances that cannot be separated into simpler substances by chemical means.