Visible light is a form of electromagnetic radiation

Chem 101 Review: Wave Particle duality of light and matter

c = nl E = hnEnergy of one photon = E = hn = hc/l

Wave properties Particle properties

Matter has wave properties (De Broglie)

l = h / mv

c=speed of light (m/s)E = energy (J)λ = wavelength (m)h = Plank’s constant (s-1)v = frequency (s-1)

Δx • Δ(mv) ≥ h / 4π

Δx = uncertainty in position (m)Δ(mv) = uncertainty in momentum (kgms-1)h =Plank’s constant (s-1)

4π = 4π

λ = wavelength (m)h = Plank’s constant (s-1)m = mass (kg)v = velocity (m/s)

The exact momentum and mass of a particle cannot be known

Electrons exist as a probability function

Chem 101 Review: Shape of orbitalsName Quantum

numberMeaning Allowed values

principal quantum number

n size 1,2,3,4…

angular momentum quantum number

ℓ shape 0,1,2,3..(n-1)0=s 1=p 2=d 3=f

magnetic quantum number

mℓ orientation – ℓ…0.. + ℓ

spin quantum number

ms spin +1/2,-1/2

isoelectronic species :same number of electronsions with same charge:

Periodic trends in Ionic Radii

Summary:

easy to form negative ions

easy to form positive ions

smallest atoms

largest atoms

Zeff= Z-SZeff= effective nuclear chargeZ= number of protonsS= shielding (ca number of core electrons)

Lewis structures

Chem 101 5

1. Find the total number of valence electrons (account for any charges) = TOTAL

2. decide connection between atoms, draw a line to represent 1 electron pair for each connection, count the electrons SHARED

3. calculate the remaining electrons = TOTAL – SHARED, assign these to the terminal atoms to make octet (or 2 for H atom)

4. any electrons left? – put them on the central atom

5. if central atom doesn’t have an octet, make multiple bonds from nonbondedelectron pairs on terminal atoms

Choose central atom correctly

least electronegative atom(not H)

oxygen rarely bonds to itself

PCl3

For PCl3: 5 (for P) + (3 × 7) (for Cl3) = 26

26 – 6 = 20

3 bonds= 6

formal charge = number of valence electrons – total assigned electrons

Ionic bonding strength

dQQEel

21

Enthalpy of reaction

CH4 + Cl2 CH3Cl + HCl

Electronegativity and Molecular Polarity

Dipoles are a vector quantity

overall dipole moment

= 0

increases with increasing chargeIncreases with decreasing ionic radius

Resonance has impact on bond lengths and strengths

7

compare NO+, NO2- and NO3

-

N O

N OO-

N OO-

N-O bond order = 1.5

N-O bond order = 1.3

N-O bond order = 3

Increase in strength and decrease in length

[ ]+

Exceptions to the octet rule

2. less than an octet

1. odd number of electrons

3. more than an octet

sp sp2sp3 sp3d2sp3d

Lone pairs take up more space

Metals, insulators and semiconductors n -typep -type - dopant has more valence electrons than the host

- adds electrons to the conduction band

- e.g. P into Si

- dopant has fewer valence electrons than the host- leads to holes in the valence band

- e.g. B into Si

Doped semiconductors

Molecular Orbital Theory

Bond order =

½ {no. bonding electrons –no. antibonding electrons}Metallic Bonding

Intermolecular forces: a summary

interacting molecules or ions

are ions involved?

are polar molecules and ions

both present?

are polar molecules involved?

are H atoms bonded to N, O or

F atoms?A) ionic bondinge.g. NH4NO3

YES

NO

B) ion-dipole forcese.g. NaCl in H2O

YES NO

E) dispersion forcesonly (induced dipoles)

e.g. Ar(l), I2(s)

D) dipole-dipole forces

e.g. H2S, CH2Cl2

C) hydrogen bondinge.g. H2O, NH3, HF

YES

NO

NO

YES

van der Waals forcesA > B > C > D > E

Bonding in solidsMolecular Solids

Consist of atoms or molecules held together by intermolecular forces (iebenzene). Covalent-Network Solids

Consist of atoms held together, in large networks or chains, with covalent bonds (egdiamond, graphite).

Ionic Solids

Consist of ions held together by ionic bonds (i.e. by electrostatic forces of attraction) (eg NaCl, CaO). Metallic Solids

Consist entirely of metal atoms: electron sea

Intermolecular forces

Polar covalent bond (strong)

intermolecular attraction (weak)

Dipole-Dipole Interactions

Hydrogen bonding

London Dispersion Forces

δ– δ+δ– δ+

Temporary dipole

Cycloalkanes - general formula:CnH2n

Alkenes - general formula: CnH2n

cistrans

HNO3

H2SO4

H2OH2O

Br2

FeBr3

HBrHBr

Chem 101 14

Functional groups to know

Carboxylic acids

Chem 101 15

produced by oxidation of alcohols

CH3CH2CH2OH + [O] CH3CH2CH

O

+ H2O CH3CH2C

O

OH

[O]

Esters formed by condensation reaction between alcohols and carboxylic acids

Amides prepared by reaction of carboxylic acid with amine

H+/OH-

condensation rxn.

amides undergo hydrolysis

+ [O]

Polymers

Chem 101 16

C CH

H

H

HC C C C

H

H

H

HH

H H

H

+ H2Oamine carboxylic

acid

Condensation polymerization: two molecules are joined to form a larger molecule by the elimination of a small molecule.

amide

Amide linkage

Ester linkage

Addition polymerization:

RRR