Chem 2C Final

Strong Fields

tend to pair electrons, tend to be diamagnetic

Weak Fields

tend to have electrons unpaired, tend to be paramagnetic

What happens when a TM bonded to a weak field ligand switches to bonding with a strong field ligand?

there is a net increase in delta

Main Group Characteristics

• group members have analogous valence shell configs

• lightest element of each group has unique characteristics

• diagonal relationships of similar properties may exist

• metallic character decreases as you approach F

Oxide Ion

O²-

Peroxide Ion

O₂^2-

Superoxide Ion

O₂^-

Alkali Metals

• the hydrogen column

• only one valence electron

• malleable, good conductors

• tend to oxidize ns^1→np^1

• readily forms oxides based on the radius of the metal

Hydrogen

strange since it is not quite metalloid, not quite halogen

• -1 charge, considered with alkali metals

• +1 charge, considered with halogens

Alkali Earth Metals

• Beryllium column

• easily oxidized to a +2 oxidation state

• Beryllium: beryllium chloride forms unique planar structures

• calcium: creates concrete w/ CaO, also makes chalk

• Barium: BaS is opaque to x-rays

General Reaction

M+Z₂(or W-Z) → M-Z_y

Group 13 (Icosagens)

• Al, Ga, In, Tl

• have a ns²np^1 electron config

• common ox states: +1, +3

• can form dimers

• Aluminum: AlCl forms unique planar structure, most abundant metal in Earth’s crust, very strong

dimers

where two identical compounds bond together

Inert Pair Effect

occurs for metals and non-metals in groups 13, 14, 15, and 16, where they all have expected charges

• nonmetals have negative charges

• metals have positive charges

• semimetals can be both negative and positive

• 13: +1, +3

• 14: +2, +4

• 15: +3, +5

• 16: +4, +6

Group 14 (Tetragens)

• sn, pb

• can form 4 bonds

• common charge of +2, +4

• Tin can be used for solders, pewter

• lead can be used for ammo, piping, storage cells in batteries

Noble Gases

• helium column

• odorless, colorless, ionizable, electro-negative, nearly ideal gases, not completely inert, can form compounds under certain conditions

• Helium: very light, LDF, unreactive, dilutent

• Neon: light emits under current

• Argon: 3rd most common gas that comprises air

• Krypton: product of fission

Group 17 (Halogens)

• F column

• electron config: ns²np^5

• F- is the most reactive becaus eit is the least polarizable

• halogens w/ oxygens form oxy acids

• other halogen compounds: teflon, Freon, PVC

Hypohalous Acid

HOX, +1

oxy acid

Halous Acid

HOXO, +3

oxy acid

Halic Acid

HOXO_2, +5

oxy acid

Perhalic Acid

HOXO₃, +7

oxy acid

Group 16 (halcogens)

• oxygen column

• oxygen: forms lots of things, includes both pi and sigma bonds

• sulfur: tends to join to itself, smells bad, forms H2SO4, rubber

Group 15 (Pnictogens)

• nitrogen column

• can exist in multiple oxidation states, +3 or +5 can give noble gas configuration

• Nitrogen: nearly inert, but out of N2 can be explosive like with TNT

• phosphorous: common ox states: +3, +5, can make lots of oxides, can create oxy acids

Group 14 (Tetragens)

• carbon, silicon, GE

• Carbon: super strong compounds, can bond w/ itself and others, creates allotropes, essential to all life

• silicon: Si-O bonds stronger than Si-Si, glass dust and sand, amorphous

Group 13 (Icosagens) B

• Boron

• true semi metal

• dopant

• can form clusters

• behaves more like silicon than aluminum

For the rxn R→ P, what is the tangent line and what is the secant line?

The tangent: the instantaneous rxn rate

the secant: the avg rate in the rexn rate

What does k depend on?

depends on reaction, temperature, and catalyst

Slow reaction speed

rate is small, rate constant is small

Fast reaction speed

rate is large, rate constant is small

The Order

the rxn is the sum of the exponents (m+n)

• m and n are usually small, positive numbers and may be equal to zero, but may also be negative or fractions

Zeroth Order Rate Law

• for a straight line, [A] vs. t

• non-concentration dependent

• m+n+…=0

First Order Rate Law

• for a straight line, ln[A] vs. t

• m+n+…=1

Second Order Rate Law

• for a straight line, 1/[A] vs. t

• m+n+…=2

Collision theory

• a & b need to hit directly

• a & b need to enter with a combined kinetic energy that is high enough to make bond formation a viable result

Collision Frequency

number of molecular collisions per unit time

Activation Energy

minimum energy above which collision results in product

• as temperature goes up, velocity and kinetic energy go up

Orientation in Space

for a bond to happen, there must be a direct hit

Transition State Theory

• when A & B first collide, a transition state between formed and unformed is created. After transition state, reaction can either proceed to products or return to reactions

• breaks down when considering quantum mechanics at high temps

• peak of activation is the transition state

A

the frequency factor

made up of (Z₀)(p)

p= proper orientation when collision occurs

Z₀= the frequency of molar collisions

Reaction Mechanisms

a step-by-step description of a chemical reaction where each step is called an elementary process (or step)

Elementary Process Typical Characteristics

• uni or bipolar

• reaction coefficients are the same as exponents in the rate law

• reactions are reversible

• intermediates appear in the same steps. an intermediate is a chemical species that appears in the elementary process but not in the overall reaction.

RDS

rate determining step, the slow reaction

• r is small… meaning very slow

• k is small… since r and k are proportional

Pseudo Steady State Hypothesis (PSSH)

states that at equilibrium, the rate of appearance and disappearance of intermediates are equal

Catalyst

• lowers the activation energy

• increases the rate of reaction so that it occurs faster

• reaction equilibrium (keq) is not affected

Homogeneous Catalysis

occurs when the reaction and catalyst are in the same phase

Heterogeneous Catalysis

occurs when the reaction and catalyst are in different phases

Michcelis-Menten Kinetics

biochemical reactions involving a single substrate

• high substance concentrations are zeroth order (enzyme works at maximum rate)

• low substance concentrations are first order

Alkanes

saturated hydrocarbon

Alkenes

unsaturated hydrocarbon

Alkynes

unsaturated hydrocarbon

Arenes

aromatic hydrocarbon

R

alkyl groups

Ar

arene, aromatic groups

Organic (or Alkyl) Halides

hydrocarbon derivative (no CO group)

R-X

Ar-X

(x is a halogen atom)

Alcohols

hydrocarbon derivative (no CO group)

R-OH

Phenols

hydrocarbon derivative (no CO group)

Ar-OH

Ethers

hydrocarbon derivative (no CO group)

R-O-R^1

Ar-O-R

Amines

hydrocarbon derivative (no CO group)

R-NH₂

Ar-NH₂

can have multiple R groups instead of H atoms on the nitrogen

Aldehydes

hydrocarbon derivatives (w/ CO groups)

R can be replaced with Ar

Ketone

hydrocarbon derivatives (w/ CO groups)

R can be replaced with Ar

Carboxylic Acids

hydrocarbon derivatives (w/ CO groups)

R can be replaced with Ar

Esters

hydrocarbon derivatives (w/ CO groups)

R can be replaced with Ar

Amides

hydrocarbon derivatives (w/ CO groups)

R can be replaced with Ar

can have multiple R groups instead of H atoms on the nitrogen

Spectroscopy

• uses electromagnetic radiation

• measures the difference between molecular states to determine information about the molecule

• analyzes the structure of the molecule based on the energy of the molecular state

Nuclear Magnetic Resonance

nucleus has a nuclear momentum called spin

when the correct radio-frequency radiation is introduced, the spins are aligned and energized

the change in energy is dependent on the environment of atoms in the molecule. determines carbon-hydrogen framework molecule

Infared Spectroscopy

when infared radiation is introduced into a sample, vibrational states are observed

determines functional groups present in the molecule

Ultraviolet Spectroscopy

when ultraviolet light is introduced into the sample, electrons in conjugated pi systems are excited to higher energy states

determines if a conjugated pi system is present in the molecule

conformations

identical molecules that differ only by their rotation in space

Primary

1 neighboring carbon

Secondary

2 neighboring carbons

Tertiary

3 neighboring carbons

Quartenary

4 neighboring carbons

Alkane

Big main branch

Alkyl

small branches off of the main alkane

1 Alkane

meth-

2 alkanes

eth-

3 alkanes

prop-

4 alkanes

but-

5 alkanes

pent-

Isopropyl

(3) alkane

essentially a tripod

t-butyl

(4) alkane

shaped like a bird foot

(don’t count the ‘t’ when alphabetizing substituents)

Oxidizing Agent

oxidizes compounds or elements in a reaction. the species that is reduced

Reducing Agent

the species oxidized in a reaction. reduces compounds or elements in a reaction

Anode

where oxidation occurs, drawn on the LHS, e- flow, pitting, corrosion (metal→ore)

Cathode

where reduction occurs, drawn on the RHS, current, plating, refining (ore→metal)

Where do electrons flow?

from the anode to the cathode

Standard Hydrogen Electrode (SHE)

assigned 0.00V, a standard

What happens when a half reaction is multiplied by a constant?

E^o does not change

E>0

spontaneous reaction, shift towards products

E<0

nonspontaneous reaction, shift towards reactants

E=0

equilibirum, no shift

Concentration Cells

consists of two half cells having the same reaction but only differ in concentrations

E=0

The reaction is driven forward if the molarity of the cathode>anode

Spontaneous

deltaG<0

E>0

Nonspontaneous

deltaG>0

E<0

Equilibrium

deltaG=0

E=0

K=Q

Primary Cell

reaction is non-reversible. battery eventually goes dead

Dry Cell

• hold charge a long time, good for emergency use

• zinc is the anode, manganese oxide is cathode, sometimes mercury

• can be acidic or alkaline

Button Battery

• high storage capacity, very small

• Anode=zinc

• cathode=silver

Secondary Cell

reaction can be reversed

Lead-Acid (Storage) Battery

• concentration cell

• can be put together to make car batteries