chapter 5: bonding theories

molecular shape

affects interactions, physical properties, and bio activity

paramagnetic

attracted by magnetic field b/c contains unpaired electrons

diamagnetic

repelled by magnetic field b/c contains only paired electrons

vsepr (definition)

predicts 3D shape of molecules, based on repulsion (max. distance and min. energy)

steric number (sn)

bonding groups + lone pairs; e- regions around central atom

electron-pair geometry

3D arrangement of all e- regions (bonding + lone pairs)

molecular geometry

3D shape of the molecule; only bonding atoms count

vsepr (steps)

bond polarity

unequal sharing of electrons b/w two atoms

permanent dipole

unequal distribution of e- by molecule geometry

dipole moment (μ)

quantitative measure of polarity

hybridization (definition)

mixed orbitals; better shaped and oriented to form bonds

hybridization (steps)

spˢᴺ⁻¹; assign geometry by sigma bonds

valence bond theory

orbitals overlap in covalent bonds

sigma bond

head-on; orbitals overlap along axis; single bonds

pi bond

side-by-side; connect unhybridized parallel p orbitals; excess in group bonds

isomers

compounds w/ same formula but different molecular structures

stereoisomers

compounds w/ same lewis structure but different 3D structures

enantiomers

compounds w/ nonsuperimposable structures

chiral

molecule that cannot be superimposed on its mirror image (like your left and right hands)

chiral center/stereocenter

atom that doesn’t change through different chiralities

molecular orbital (definition)

combine atomic orbitals; e- delocalized (not at one bond/atom)

molecular orbital (steps)

draw highest level orbitals; fill from lowest energy (bottom); σ before π, unless BCN

bonding orbital (σ, π)

lower energy; e- between nuclei

antibonding orbital (σ, π)

higher energy; no e- between nuclei

bond order (equation)

(bonding electrons - antibonding electrons) / 2

sp (steric number)

steric number = 2

sp² (steric number)

steric number = 3

sp³ (steric number)

steric number = 4

sp³d (steric number)

steric number = 5

SN = 2 (geometry, by lone pairs)

linear

SN = 3 (geometry, by lone pairs)

trigonal planar → bent (angular)

SN = 4 (geometry, by lone pairs)

tetrahedral → trigonal pyramidal → bent (angular)

SN = 5 (geometry, by lone pairs)

trigonal bipyramidal → seesaw → t-shaped → linear

SN = 2 (angle, by lone pairs)

180°

SN = 3 (angle, by lone pairs)

SN = 4 (angle, by lone pairs)

109.5° → <109.5° → <109.5°

SN = 5 (angle, by lone pairs)

(90°, 120°) → (<90°, <120°) → <90° → 180°

CO₃²⁻

Carbonate

HCO₃⁻

hydrogen carbonate; bicarbonate

CN⁻ Cyanide

CIO⁻ Hypochlorite

CIO₂⁻ Chlorite

CIO₃⁻ Chlorate

CIO₄⁻ Perchlorate

N₃⁻ Azide

NH₄⁺ Ammonium

NO₂⁻ Nitrite

NO₃⁻ Nitrate

OH⁻ Hydroxide

SO₃²⁻ Sulfite

SO₄²⁻ Sulfate