Ionic, Covalent, and Metallic Bonds: Introduction to ionic, covalent, polar covalent and metallic bonds.
The link address is: http://www.khanacademy.org/science/chemistry/v/ionic--covalent--and-metallic-bonds
The link address is: http://www.khanacademy.org/science/chemistry/v/ionic--covalent--and-metallic-bonds