Chemistry C2

Chemistry C2

1. chemical bonding

   • Covalent bonding-When atoms of non-metallic elements join together by sharing electrons
     • When two atoms share a pair of electrons
   • Ionic bonding-(metallic elements) Ionic compounds are held together by strong forces between the oppositely charged ions.
     • Giant ionic structures
       • High melting points, conduct electricity when dissolved in water.
     • Giant covalent strutures
       • Covalently bonded substances with giant structures have very high melting points
         • Diamond is a form of carbon, with atoms that form four covalent bonds
           • Graphite is another form of carbon where the carbon atoms form layers that can slide over other
             • Graphite can conduct electricity because of delocalised electrons
   • Formulae
     • Charges on ions cancel eachother out
       • CaCl2 (one Ca2+ ion for every two Cl- ions
   • Simple molecules
     • low melting points, boiling points
       • No overall charge, can't conduct electricity
         • Weak intermolecular forces-low m and b points