Matter & Energy

Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.


Hydrolysis, type of chemical reaction in which a molecule of water, formula HOH, reacts with a molecule of a substance AB, in which A and B represent either atoms or groups of atoms. In the reaction the water molecule breaks into the fragments H+ and OH-; and the molecule AB breaks into A+ and B-; the fragments then join to give the final products AOH and HB. This kind of reaction is called a double decomposition or an exchange.