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
An element is a substance composed of identical atoms. This definition was one of the cornerstones of John Dalton's atomic theory, but it too was made obsolete by the discovery of isotopes.Atoms of the same element have different numbers of neutrons in their nuclei.n other words, all atoms of an element have the same atomic number. This modern definition resolves some sticky situations encountered with older definitions: The definition above doesn't make element and mixture mutually exclusive classifications of matter.