Science, Tech, Math › Science Simple Alkyne Chains Nomenclature of Simple Alkyne Chain Molecules Share Flipboard Email Print Science Photo Library/Getty Images Science Chemistry Molecules Basics Chemical Laws Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated February 06, 2019 An alkyne is a molecule made up entirely of carbon and hydrogen where one or more carbon atoms are connected by triple bonds. The general formula for an alkyne is CnH2n-2 where n is the number of carbon atoms in the molecule.Alkanes are named by adding the -yne suffix to the prefix associated with the number of carbon atoms present in the molecule. A number and dash before the name denotes the number of the carbon atom in the chain that begins the triple bond.For example: 1-hexyne is a six carbon chain where the triple bond is between the first and second carbon atoms.Click image to enlarge the molecule. Ethyne The chemical structure of ethyne. Todd Helmenstine Number of Carbons: 2Prefix: eth- Number of Hydrogens: 2(2)-2 = 4-2 = 2Molecular Formula: C2H2 Propyne The chemical structure of propyne. Todd Helmenstine Number of Carbons: 3Prefix: prop- Number of Hydrogens: 2(3)-2 = 6-2 = 4Molecular Formula: C3H4 Butyne The chemical structure of 1-butyne. Todd Helmenstine Number of Carbons: 4Prefix: but- Number of Hydrogens: 2(4)-2 = 8-2 = 6Molecular Formula: C4H6 Pentyne The chemical structure of 1-pentyne. Todd Helmenstine Number of Carbons: 5Prefix: pent- Number of Hydrogens: 2(5)-2 = 10-2 = 8Molecular Formula: C5H8 Hexyne The chemical structure of 1-hexyne. Todd Helmenstine Number of Carbons: 6Prefix: hex- Number of Hydrogens: 2(6)-2 = 12-2 = 10Molecular Formula: C6H10 Heptyne The chemical structure of 1-heptyne. Todd Helmenstine Number of Carbons: 7Prefix: hept- Number of Hydrogens: 2(7)-2 = 14-2 = 12Molecular Formula: C7H12 Octyne The chemical structure of 1-octyne. Todd Helmenstine Number of Carbons: 8Prefix: oct- Number of Hydrogens: 2(8)-2 = 16-2 = 14Molecular Formula: C8H14 Nonyne The chemical structure of 1-nonyne. Todd Helmenstine Number of Carbons: 9Prefix: non- Number of Hydrogens: 2(9)-2 = 18-2 = 16Molecular Formula: C9H16 Decyne The chemical structure of 1-decyne. Todd Helmenstine Number of Carbons: 10Prefix: dec- Number of Hydrogens: 2(10)-2 = 20-2 = 18Molecular Formula: C10H18 Isomer Numbering Scheme The chemical structures of the three isomers of the hexyne alkyne molecule: 1-hexyne, 2-hexyne and 3-hexyne. The carbon atoms are numbered from left to right in red. The number corresponds to the first carbon of the triple bond of the alkyne. Todd Helmenstine These three structures illustrate the numbering scheme for isomers of alkyne chains. The carbon atoms are numbered from left to right. The number represents the location of the first carbon atom that is part of the triple bond.In this example: 1-hexyne has the triple bond between carbon 1 and carbon 2, 2-hexyne between carbon 2 and 3, and 3-hexyne between carbon 3 and carbon 4.4-hexyne is identical to 2-hexyne and 5-hexyne is identical to 1-hexyne. In these cases, the carbon atoms would be numbered from right to left so the lowest number would be used to represent the molecule's name.