In chemistry, non-aromatic and non-cyclic (acyclic) organic compounds are called aliphatic. They include not only the fatty acids and other derivatives of the paraffin hydrocarbons, but also unsaturated compounds, such as the ethylene (alkene) and acetylene (alkyne) series. The simplest aliphatic compound is methane (CH4). Chemistry (in Greek: χημεία) is the science of matter that deals with the composition, structure, and properties of substances and with the transformations that they undergo. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... A cycle is anything round, in the physical sense (e. ... Acyclic can mean any of the following: In chemistry, an acyclic compound is a hydrocarbon compound having an open chain. ... Organic has several meanings and related topics. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ... Paraffin is a common name for a group of high molecular weight alkane hydrocarbons with the general formula CnH2n+2, where n is greater than about 20, discovered by Carl Reichenbach. ... The term saturation generally means thoroughly full, and can refer to the following: In chemistry, see saturation (chemistry) for a number of meanings. ... Ethylene or ethene is the simplest alkene hydrocarbon, consisting of two carbon atoms and four hydrogens. ... An alkene is an unsaturated hydrocarbon containing at least one carbon-carbon double bond. ... The chemical compound acetylene, also called ethyne, was discovered in 1836 by Edmund Davy, in England; its chemical formula is C2H2 and its structure is: Acetylene is a colorless and extremely flammable gas at standard temperature and pressure, with a melting point of -80. ... Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms. ... The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4. ...