Walz Chapter Unit 5

Intramolecular

bonding forces that hold the atoms of a molecule together

Ionic bonding

(Intramolecular) - metal & nonmetal transfer of e-

covalent bonding

(Intramolecular) -All nonmetals sharing e-

Metallic Bonding

(Intramolecular) All metals sea of e-

Intermolecular

between different molecules, across longer distances, electrostatic +/- attraction

London Dispersion

(Intermolecular) Between individual atoms that are dipoles (Attraction)

a. atoms with ordinarily spherical shapes can lose their symmetry and become dipoles

b. this produces an atom with oppositely charged ends

c. a dipole created by the presence of another dipole is an induced dipole

d. the force of attraction between induced dipoles is called a London Dispersion Force

Dipole - Dipole Force

(Intermolecular) Between polar molecules not containing hydrogen

a. many molecules in nature are polar because of unequal electron distribution in the molecules

b. the positive end of one dipole will form an attraction to the negative end of its neighboring dipole

c. this force of attraction between polar molecules is called a dipole-dipole force

d. these forces can cause boiling points for substances to increase due to increased energy required to break the attractions and free the molecules into a gaseous state

Hydrogen Bonding

(Intermolecular) Between polar molecules containing hydrogen. [Nitrogen, Oxygen, Hydrogen]

a. when hydrogen bonding is combined with a highly electronegative nonmetal, the resulting bonds have a very high polarity because if the big EN difference

b. consequently, the more positive hydrogen end of one molecule is strongly attracted to the more negative nonmental (Groups 16 or 17) end of its neighboring molecule

c. this very strong intermolecular force is called Hydrogen Bond

linear

Molecule contains on 2 or 3 atoms, central atom has no unshared pairs

Bond angle - 180

Hybridization - sp

Trigonal planar

Flat molecule contains central atoms with no unshared elections and 3 surronding atoms.

Bond angle - 120

Hybridization sp2

Tetrahedral

1 or more central atoms with no unshared electrons & 4 surronding bonds

Bond angle - 109.5

Hybridization - sp3

Pyramidal

1 central atom (1 unshared pair) surronded by 3 atoms

bond angle - 107

Hybridization sp3

Bent

1 central atom with 2 unshared pairs surronded by 2 atoms

Bond angle - 105

Hybridization sp3

Ionic

3.3 - 1.7

Polar Covalent

1.6 - 0.4

invole unequal electron sharing (one atoms pulls harder on the electron pair)

Nonpolar covalent

0.3 - 0

bonds involve an equal sharing of electron pairs between atoms. (both pull fairly equally on the electron pair)

VSEPR theory

valence shell electron pair repulsion theory

a. there is a natural tendency for electron pairs to repel each other

b. in a small molecule, the valence electron pairs will be arranged as far apart as possible

Molecular Polarity

a. if a molecule as a whole is polar it means the elctron distribution is uneven.

b. if a molecule is nonpolar it means the electron distribution is even

Bond Length

a measure of the distance between atoms that are bonded together

usually represented in nm

a) as you move down a group in the periodic table, the atoms form longer bonds

b) multiple bonds are shorter than single bonds

Ex.

C-C - 0.154 nm

C--C 0.134 nm

C---C 0.120nm

Hybridization

refers to the blending of orbitald during bonding.

number of hybrid orbitals = combinations of Sp and Up (central atoms) for molecule