Chemical Reactions

Rearranging atoms



In a chemical reaction atoms are rearranged to form different substances. The atoms are not created noe destroyed. There are the same number of each type of atom present before and alter the reaction - they are just joined up in different combinations. This products of a reaction have different properties than the reactants. As not atoms have been created or destroyed, total mass of all the atoms involved stays the same.

Thermal decomposition

Metal carbonate decompose when they are heated to form an oxide and carbon dioxide. Some carbonates decompose more easily than others (decomposition happens at a lower temperature).

Precipitation reactions

A precipitation reaction happens when two soluble substances react together to form a product which is insoluble. The insoluble product is the precipitate. lead nitrate + potassium iodide = potassium nitrate + lead iodide

(soluble)        (soluble)                  (soluble)                 (insolubl- forms a precipitate)