Ch9_4_BondProps - Bond Properties • What is the effect of...

Info iconThis preview shows page 1. Sign up to view the full content.

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

Unformatted text preview: Bond Properties • What is the effect of bonding and structure on molecular properties? 1 2 Bond Order: # of bonds between a pair of atoms of Single bond Bond Order Bond Order Fractional bond orders occur in molecules with resonance structures. •• •• Consider NO2N N 3 Double bond •• O •• The N—O bond order = 1.5 Bond order = •• • O •• • ••• O ••• •• O •• Total # of e- pairs used for a type of bond Total # of bonds of that type Buckyball in HIV-protease Acrylonitrile Triple bond Bond order = 3 e- pairs in N—O bonds 2 N— O bonds Bond Order Bond Order Bond order is proportional to two important bond properties: 4 5 6 Bond Length Bond Length • Bond length is the distance between the nuclei of two bonded atoms. Bond Length Bond length depends on size of bonded atoms. atoms. (a) bond strength (b) bond length 110 pm 123 pm 414 kJ 745 kJ H—F H—Cl H—Cl Bond distances measured Bond distances measured using CAChe software. In using CAChe software. In Angstrom units where 1 A Angstrom units where 1 A = 10-2 pm. = 10-2 pm. m. H—I Page 1 7 8 9 Bond Length Bond length depends on bond order. order. Bond Strength • —measured by the energy req’d to break a bond. See Table 9.9 H—H H—H C—C C=C C≡C N≡N Bond Strength • —measured by the energy req’d to break a bond. See Table 9.9. • BOND STRENGTH (kJ/mol) BOND (kJ/mol) 436 346 602 835 945 Bond distances measured Bond distances measured using CAChe software. In using CAChe software. In Angstrom units where 1 A Angstrom units where 1 A = 10-2 pm. = 10-2pm. pm. The GREATER the number of bonds (bond order) the HIGHER the bond strength and the SHORTER the bond. 10 11 Bond Strength Bond HO—OH O=O •• •• O O •• •• •• •• O O •• •• O• O• •• • •• • Order Length Strength We’re Done! 1 2 1.5 142 pm 121 128 210 kJ/mol kJ/mol 494 ? Page 2 ...
View Full Document

Ask a homework question - tutors are online