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.


Alkaloids, group of mildly alkaline compounds, mostly of plant origin and of moderate molecular complexity. Even in very small amounts, the alkaloids produce strong physiological effects on the body. All contain nitrogen atoms that are structurally related to those of ammonia.

Nearly 3000 alkaloids have been recorded; the first to be prepared synthetically (1886) was one of the simplest, called coniine, or 2-propyl piperidine, C5H10NC3H7. It is highly poisonous; less than 0.2 g (0.007 oz) is fatal. Coniine, obtained from seeds of the hemlock, was the poison used in the execution of Socrates. Some 30 of the known alkaloids are used in medicine. For example, atropine, obtained from belladonna, causes dilation of the pupils; morphine is a painkiller; quinine is a specific remedy for malaria; nicotine is a potent insecticide; and reserpine is a valuable tranquilizer.