Metallic Bonding

Metallic Bonding Metallic Bond – the force that holds metal atoms together Metals do not form covalent bonds with one another because they do not have enough electrons in their outer shells to form stable octets. Even though they do not form covalent bonds, they do share electrons. They release their electrons to a shared pool of electrons. Imagine a metal as a non-rigid arrangement of metal ions in a sea of free electrons.

Sea of electrons The valence electrons delocalize from the positive atoms.

Melting point According to the strength of the bond Depends on the number of electrons the atom can delocalize to its “sea” Group 1 metals have the lowest m.p. since they only have one valence electron to contribute; also they have the largest radius so the positive nucleus is further from the sea Transition metals have particularly high melting points because they can involve the d electrons in their delocalization in addition to the s e’s.

Conductivity Electrical Thermal Metals conduct electricity well because the electrons can flow in the sea. Thermal Metals also conduct heat well because the freely moving electrons have kinetic energy.

Strength and Workability Malleable – can be beaten into sheets Ductile – can be stretched into wires BECAUSE the atoms are able to roll over each other without breaking bonds Stress can be put on the metal and released and the atoms will go back to normal because metals are ELASTIC.

Animation Websites http://cd1.edb.hkedcity.net/cd/science/chemistry/resource/animations/metallic_bond/metallic.html http://www.ausetute.com.au/metallic.html http://www.drkstreet.com/resources/metallic-bonding-animation.swf