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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.
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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 (CF2Cl2) CH4 + 2Cl2 + 2F2 CF2Cl2 + 2HF + 2HCl
Homework • Pg. 407 # 47 – 55 (odd)