17 - Chemistry 1000 Lecture 17: Bond properties Marc R....

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chemistry 1000 Lecture 17: Bond properties Marc R. Roussel Bond order and bond length Bond order: half the number of electrons shared in a covalent bond (number of lines between two atoms in a non-resonant Lewis structure) I In molecules with resonance structures, the bond order is the average over all equally good structures. Example: CC bond order in benzene = 1 2 (1 + 2) = 3 2 I All other things being equal, higher bond orders correspond to shorter bonds. Compound CC bond order Bond length/pm H 3 CCH 3 1 152 . 4 Benzene 3 2 139 H 2 C=CH 2 2 133 . 05 HC CH 3 120 . 4 Bond dissociation enthalpies Definition: Enthalpy change for the breaking of a covalent bond in the gas phase Symbol: bd H Example: H 2(g) 2H (g) , bd H = 435 . 996kJ / mol Example: CH 4(g) CH 3(g) + H (g) , bd H = 438 . 3kJ / mol Note: The textbook deals in bond energies rather than enthalpies. Both are valid, and quantitatively they are not very different. I In general, bond dissociation enthalpy depends on the particular molecule in which the bond occurs, not just on the atoms involved....
View Full Document

Page1 / 13

17 - Chemistry 1000 Lecture 17: Bond properties Marc R....

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online