Aluminum A metallic chemical element, symbol Al, atomic number 13, atomic weight 26.98154, in group 13 of the periodic system. Pure aluminum is soft and lacks strength, but it can be alloyed with other elements to increase strength and impart a number of useful properties. Alloys of aluminum are light, strong, and readily formable by
Alkene الألكينات و الألكاينات (الفصل 3 ) Alkenes and Alkynes Alkene One of the class of acyclic hydrocarbons containing one or more carbon-tocarbon double bonds. Alkenes (also called olefins) and alkynes (also called acetylenes) together constitute the family of organic compounds called unsaturated hydrocarbons, since they contain less than the number of hydrogens found in
Alkane A compound with the general formula CnH2n+2· Alkanes are open-chain (aliphatic or noncyclic) hydrocarbons with no multiple bonds or functional groups. They consist of tetrahedral carbon atoms, up to 105 carbons or more in length. The C-C bonds are formed from sp3 orbitals, and there is free rotation around the bond axis. Alkanes provide