Strengths of Covalent Bonds

Strengths of Covalent Bonds - However, this is a relatively...

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Strengths of Covalent Bonds The stability of a molecule is a function of the strength of the covalent bonds holding the atoms together. How do we measure the strength of a covalent bond? Bond-dissociation energy (i.e. "bond energy") Bond energy is the enthalpy change ( H, heat input) required to break a bond (in 1 mole of a gaseous substance) What about when we have a compound which is not a diatomic molecule? Consider the dissociation of methane : There are four equivalent C-H bonds, thus we can that the dissociation energy for a single C-H bond would be: D (C-H) = (1660/4) kJ/mol = 415 kJ/mol Note: The bond energy for a given bond is influenced by the rest of the molecule.
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Unformatted text preview: However, this is a relatively small effect (suggesting that bonding electrons are localized between the bonding atoms). Thus, the bond energy for most bonds varies little from the average bonding energy for that type of bond Bond energy is always a positive value - it takes energy to break a covalent bond (conversely energy is released during bond formation) Average bond energies: Bond (kJ/mol) C-F 485 C-Cl 328 C-Br 276 C-I 240 C-C 348 C-N 293 C-O 358 C-F 485 C-C 348 C=C 614 C= C 839 The more stable a molecule (i.e. the stronger the bonds) the less likely the molecule is to undergo a chemical reaction...
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This note was uploaded on 11/22/2011 for the course CHEMISTRY CHM1025 taught by Professor Laurachoudry during the Fall '10 term at Broward College.

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Strengths of Covalent Bonds - However, this is a relatively...

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