CHEM 140A Lecture Notes - Lecture 1: Trigonal Pyramidal Molecular Geometry, Valence Electron, Electron Affinity

• School: UCSD
• Department: Chemistry and Biochemistry
• Course: CHEM 140A
• Professor: Joseph M Oconnor

Document Summary

9/22/16 covalent bonding: sharing electrons: atoms attracted to each other where electrons attracted to opposite nucleus. Why do elements react: ele(cid:373)e(cid:374)ts that are ele(cid:272)tro(cid:374) ri(cid:272)h a(cid:374)d o(cid:374)e that"s ele(cid:272)tro(cid:374) defi(cid:272)ie(cid:374)t rea(cid:272)t (cid:271)e(cid:272)ause the(cid:455) are attracted to each other. Covalent bonds: elements in the middle of the periodic table have problem with electron affinity and ionization potential: carbon obtains octet by sharing electrons, compromise: electron sharing. Most bonds between covalent and ionic: polar covalent. 2 ele(cid:373)e(cid:374)ts (cid:449)ith 2 differe(cid:374)t ele(cid:272)tro(cid:374)egati(cid:448)it(cid:455)"s, (cid:272)auses polar attra(cid:272)tio(cid:374)s. Higher electronegativity causes more negative partial charges. When drawing 3d molecules, wedge should be below dashed lines: wedge means the bond is protruding out, dash means the bond is behind the plane saturated h(cid:455)dro(cid:272)ar(cid:271)o(cid:374): (cid:449)here there"s a (cid:373)a(cid:454)i(cid:373)u(cid:373) (cid:374)u(cid:373)(cid:271)er of h per c. Charges when formal effective electron count around the nucleus differs from valence electron count. Effective electron count: each bond with 2 shared electrons counts as 1 electron; one pair counts as 2 electrons.