Metallic Bonds and Bond Energy

Metallic Bond Bond that exists between metal atoms Alloy – two or more different metal atoms bonded together

Electron Sea Model Metal atoms give up valence electrons and form + ions The released electrons move freely around the + metal ions

Properties of Metallic Bonds Good conductors of electricity – free electrons Malleable and ductile – not in rigid position so ions can be shaped and drawn into wires Conduct heat because of free electrons Lusterous – absorb and emit light in regular pattern due to free electrons

Bond Energy Energy, in kJ, required to break a bond in 1 mole of a compound Bond energies given in Table 8.4 (pg. 373)

Enthalpy (  H) Bond energies can be used to calculate an approximate energy of reaction  H can be thought of as the energies required to break old bonds plus the energies released when new bonds are formed  H =  D(bonds broken) -  D(bonds formed)

Example Use bond energies to calculate the  H for the reaction of methane with chlorine and fluorine to give freon (CF 2 Cl 2 ) CH 4 + 2Cl 2 + 2F 2  CF 2 Cl 2 + 2HF + 2HCl

Homework Pg. 407 # 47 – 55 (odd)