CHEM 1A Lecture Notes - Lecture 20: Bond Energy, Electron Affinity, Covalent Bond

• School: UCSB
• Department: Chemistry and Biochemistry
• Course: CHEM 1A
• Professor: BERNT C M

Document Summary

Exam 2 is a week from this friday. Review session: tue 11/27 5:00 - 6:00, lsb 1001. Higher the bond energies harder to break the bond. H = (bonds broken) - (bonds formed) To break a bond, energy is required to add in. To form a bond, energy is released (recall the process of electron affinity where energy is release by joining a free electron to an atom) If h negative, release heat (exothermic) , tend to be favorable. If h positive, absorb heat (endothermic), tend to be less favorable. Molecular structure and valence shell electron pair repulsion (vsepr): Vsepr: since like charges repel, valence electron pairs want to be as far away as possible in 3d. Notice electron pairs include both bonds and lone pairs. Steps to finding electronic geometry : draw lewis structure, determine steric number (sn) = count all atoms and lone pairs attached to the central atom, determine the shape based on the steric number.