CH 101 Varner

when atoms of similar electronegativity (generally 2 nonmetals) share electrons

Covalent bonds

Electrostatic attraction between a cation and anion Oftentimes (but not always), this is between a metal cation and non-metal anion

Ionic bonds

1) Each atom that requires an octet has an octet

2) The total number of atoms with nonzero formal charges is minimized

Resonance Structure Hierarchy Rules:

Pi bonds are only if there is more than one bond between two molecules

Sigma vs Pi bonds

just p

Pi orbital hybridization is

1) # of atomic orbitals in = # of molecular orbitals out

2) The lower energy molecular orbital is termed a bonding orbital

3) The higher energy molecular orbital is termed an antibonding orbital and is labeled with “*”

Molecular Orbitals (MO)

BO = ½(BE-ABE*)

MO Bond Order

Molecule has at least one unpaired electron

Paramagnetic

Exist within a single molecule. The covalent or ionic bonds between atoms.

Intramolecular Forces

Exist between 2 or more molecules. The attractive forces between two molecules that keep them close together.

Intermolecular Forces

the larger the molecule, the larger the amount of London dispersion forces.

All molecules possess dispersion forces. However,

Requirements One molecule with a H-N, H-O, or H-F covalent bond. A second molecule with a N, O, or F atom.

The δ+ H atom of one molecule is attracted to the δ- N, O, or F atom of a second molecule

Hydrogen Bonding

Gases = thermal > intermolecular

Liquid = equal

Solid = thermal < intermolecular

Thermal vs intermolecular forces

the higher the melting point or boiling point

The greater the number of intermolecular forces

easy escape from liquid phase

Low atmospheric pressure =

difficult escape from liquid phase

High atmospheric pressure =

Sublimation

Solid to gas

deposition

Gas to solid

condensation

Gas to liquid

evaporation

Liquid to gas

freezing

Liquid to solid

melting

Solid to liquid

Nonpolar solutes are soluble in nonpolar solvents.

Polar solutes are soluble in polar solvents

“Like Dissolves Like”

hydrophobic

Nonpolar solutes are

Molar concertation (moles solute / liters solution)

What does “M” stand for?

grams/mL

Density

London dispersion are effected by

Mass and # of molecules, not electronegativity

Vapor Pressure is opposite

Boiling point

Hydrophobic

No polar

Hydrophilic

Polar

Rows 3a and below

Can break octet rule