Explanations of some words used on this site:
Clean tech: Clean technology is sustainable technology and technology built upon the use of renewable resources.
Compound: A compound is a molecule made up of two or more atoms, usually of different elements. Each compound has distinct chemical properties.
Ductile: A ductile metal can be drawn into wires.
Electrolysis: A battery uses a chemical reaction to generate electricity. Electrolysis is the opposite - plunge positive and negative electrodes in water, and current will flow between them. Oxygen collects at one electrode and hydrogen at the other as the water is broken down into its elements. Other chemical solution work the same way.
Element: An element is a substance made up of a single kind of atom. Each element has its own chemical properties, and those properties determine the color, hardness, and other characteristics that we see. Chemists organize elements on the periodic table and give each element a unique one- or two-character abbreviation.
Ion: An ion is an atom with an electric charge because it has more or fewer electrons than normal. A molecule dissolved in a liquid may separate into positive and negative ions.
Isotope: The identity of an element depends on how many protons are in its nucleus. For example, hydrogen always has 1 proton; othewise it's a different element. Atoms of the same element can have different amounts of neutrons, however. These are isotopes. They are chemically identical but have slightly different densities.
Malleable: A malleable metal can be shaped and, in particular, beaten into thin sheets.
Radiation - Radiation can refer to any kind of emanating energy, such as light from the sun. It usually refers, though, to atomic decay. Atoms of some elements are unstable and will randomly decay, emitting radiation. The three types of radiation are alpha radiation (helium nucleii, stopped by paper or a few inches of air), beta radiation (electrons, stopped by a sheet of metal), and gamma radiation (the most energetic, stopped by thick, dense shielding).
Renewable: Renewable energy comes from sources that do not diminish on human time scales. Some energy sources, such as sun and wind, do not deplete. Other sources, such as wood and other biomass, can be replenished as fast as they are used.
Solution: In chemistry, a solution is a liquid containing a dissolved solid or gas. The liquid is the solvent; the dissolved substance is the solute. Some liquids, such as water, are good solvents as they can dissolve many things. A solvent can hold only a certain capacity. As the temperature goes up, its capacity for dissolved solids increases, while its capacity for gases decreases.
Substance: A substance is made up of one kind of molecule and thus is an element or a compound. Solutions and metal alloys are not single substances.
Sustainable: This word can describe big human projects such as cities, food distribution, or energy collection. A sustainable system does not degrade over time. This generally means it uses renewable energy and manages its pollution and other side effects.