From Citizendium, the Citizens' Compendium
- Chemistry : The science of matter, or of the electrical or electrostatical interactions of matter.
- Chemical elements : In one sense, refers to species or types of atoms, each species/type distinguished by the number of protons in the nuclei of the atoms belonging to the species/type, each species/type having a unique number of nuclear protons; in another sense, refers to substances, or pieces of matter, each composed of multiple atoms solely of a single species/type.
- Organic chemistry : The scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds of carbon and hydrogen, which may contain any number of other elements.
- Coal : A carbon-containing rock formed by the effect of bacteria, heat and pressure on the debris from the decay of ferns, vines, trees and other plants which flourished in swamps millions of years ago.
- Hydrocarbons : A class of molecules that contain only carbon and hydrogen atoms.
- Life : Living systems, of which biologists seek the commonalities distinguishing them from nonliving systems.
- Natural gas : A gas consisting primarily of methane (CH4) which is found as raw natural gas in underground reservoirs, as gas associated with underground reservoirs of petroleum crude oil, as undersea methane hydrates and as coalbed methane in underground coal mines.
- Periodic Table of Elements : A tabular method of displaying the chemical elements.
- Petrochemical : Chemical products made from the hydrocarbons present in raw natural gas and petroleum crude oil.
- Petroleum crude oil : A naturally occurring, flammable liquid found primarily in underground geological formations and consists of a complex mixture of hydrocarbons of various molecular weights plus other organic compounds.