MCAT Chem

Photon energy

hf = hc / wavelenght

Lewis Base

A chemical species that donates a pair of electrons

Lewis Acid

A chemical species that accepts a pair of electrons

Keq < 1

1. favors reactants

2. + Delta G

3. nonspontaneous

Keq = 0

1. nothing favored; equal

2. 0 = delta G

3. at equilibrium

Keq > 1

1. favors products

2. - delta G

3. spontaneous

Ionic bond

A bond that results from electrons being transferred completely from one atom to another

Covalent bond

A bond in which both atoms contribute electrons to be shared between the nuclei of the two atoms an electron coming from both atoms

Coordinate ionic bond

Doesn’t exist.

Coordinate covalent bond

A type of covalent bond where the electrons shared comes from one atom

Coordinate number

The total number of atoms, ions, or molecules directly bonded to a central atom

Ionization energy

The minimum energy required to remove the most loosely bound electron. Trend: increases right and up.

Henderson Hasselbalch Equation

pH = pKa + log ([A-]/[HA])

Hess’s Law

Delta H (enthalpy) = sum of delta Hf products - sum of delta Hf reactants

Ideal gas law

PV=nRT

ideal gas constant R

R = 8.314 J / mol

R = 0.082 L atm / mol K

Ideal molar volume for ideal gases

22.4 L/mol

Strong Acids

• HCl

• HBr

• HI

• HClO4

• HNO3

• H2SO4

Strong Bases

• LiOH

• NaOH

• KOH

• RbOH

• CsOH

• Ca(OH)2

• Sr(OH)2

• Ba(OH)2

Ka and Kb relation to Kw

Ka x Kb = Kw

Relationship between Ka and pKa

pKa = - log (Ka)

pH equation for acid concentration

pH = -log [H3O+]

pOH equation of base concentration

pOH = -log [OH-]

Equation to find Ka

Ka = [H3O+] [ A-] / [HA]

Equation to find Kb

Kb = [BH+] [OH-] / [B]

Gamma Decay

No change in atomic number. Radiation is emitted through gamma rays like high energy photons when the nucleus moves from a higher energy state to a lower energy state

Alpha Decay

A He particle of neutrons and protons is removed from the nucleus as radiation called the alpha particle. The result is a daughter nucleus with an atomic number decreased by 2

Beta minus decay

Releases an electron and increaes atomic number by 1

Beta plus decay

Releases a positron and decreases the atomic number by 1

Oxidation # Rules

1. Free elements (H2,O2,ect) = 0

2. Hydrogen = +1

3. Group 1 = +1

4. Group 2 = +2

5. Metals are dependent on the other atoms

6. Group 17 / halgoens = -1

7. Oxygen = -2 (with few acceptions)

What happens if a molecules oxidation number goes up

It gets oxidized and it is the reducing agent

What happens if a molecules oxidation number goes down

It gets reduced and is the oxidation agent

What happens if there is no change in the oxidation number

No redox reaction occured

Electron affinity trend

Increases to the right and up

What happens to boiling point when pressure is decreased

boiling point decreases

Avagadro’s Number

6.02 × 10²3

Inductive effect

The shifting of electrons from less electronegative atom towards more electronegative atoms

Absolute configuration the amino acids

Most AAs S & L. Cystene = S & R. Glycine = no stereocenter

SN1 rxn facts

• substrate only in the rate

• 3 > 2 > 1

• weak nucleuophile

• polar protic solution

• sterochem = racemic

SN2 rxn facts

• substrate & nucleophile rate dependent

• 1 > 2 > 3 (no rxn)

• strong nu ( - charge)

• polar aprotic (DMSO, acatone)

• inverted sterochem

Charge of amino acids at pH 2

+1 cation —> N terminus = +, C terminus = 0

Charge of amino acids at neutral pH

0 zwitterion —> N terminus = +, C terminus = -

Charge of amino acid at pH 9

-1 anion —> N terminus = 0, C terminus = -

Isomerization

The process in which a molecule is transformed into an isomer with a different chemical structure (but same chemical makeup) ex: enolization, tautomerization

Electron Capture

Type of beta decay where a proton captures an electron near the nucelus and converts into a neutron without a positiron or electron emission and decreases atomic number

Polarizability

The extent to which an electron cloud of an atom can be distorted by an external charge or by an applied electric field to produce a dipole. Increases down and to the left

Electronegativity

The tendency of an atom to attract electrons within a bond. Increases up and to the right

Electron affinity

The tendency of an atom to accept an additional electron by measuring the energy change when an electron is added to an atom. increases right and up

Ionization energy

Measures the energy required to remove an electron from an atom. increases right and up

Standard temperature and pressure (STP) conditions

• standard pressure = 1 atm

• standard temp = 273K or 0C

• 1 mole of any gas at STP has a volume of 22.4L

Qualifications to be arromatic

1. Conjugated pi bonds in a cyclic structure

2. Unhybridized p orbitals present in each atom

3. Plana geometry, forming a continuous ring of parallel, overlapping unhybridized p orbitals

4. 4n+2 pi electrons (Huckels rule), where n is a non-negative integer

Dispersion

The phenomenon of different frequencies of light having slightly different refractive indicies

Heat of combustion

The measure of the energy released when the compound is combusted with oxygen. The amount of energy to break bonds within a molecule

How to find the energy of activation

The activated complex minus the energy of the reactants

What is aceylation?

The addition of an acyl group (CH3CO)

What group is alkali metals

group 1

what group is alkaline earth metals

group 2

Linear

1. 2 Electron group

2. Bond angle 180

Trigonal Planar

1. 3 Electron groups

2. Bond angle 120

Tetrahedral

1. 4 Electron Groups

2. Bond Angle 109.5

Trigonal Bipyramidal

1. 5 Electron Groups

2. Bond angles 90 and 120

Octahedral

1. 6 Electron groups

2. Bond angle 90

What is -CHO the condensed form for

Aldehyde

OH IR peak

3300 cm

Carboxylic acid peak

3000 cm

Amide / N-H peak

3300 cm

Carbonyl peak

1750 cm

sp3 carbons NMR

0 to 3 ppm

sp2 carbons NMR

4.6 6o 6.0 ppm

sp carbons NMR

2 to 3 ppm

Aldehyde NMR

9 to 10 ppm

Carboxylic acids NMR

10.5-12 ppm

Aromatics NMR

6.0 - 8.5 ppm

Absorbance and concentration relationship (if path length and wavelength are constant)

A1/C1=A2/C2

London Dispersion forces

Weak, temporary intermolecular forces are present in all atoms and molecules cause by random electron motion forming instantaneous dipoles

Critical Point

The end point of the liquid-gas coexistence curve representing the specific temp and pressure above which distinct liquid and gas phases exist

Sublimation

Solid to gas

What is it?

Amide

What is it?

Amine

What is it?

Imine

What is it?

Acyl Halide

What is it?

Alcohol

What is it?

Ether

What is it?

Thiol

What is it?

Sulfide

What is it?

Ketone

What is it?

Aldehyde

What is it?

Carboxylic Acid

What is it?

Acyl Halide

What is it

Anhydride

What is it?

Ester

Important oxidizing reagants

PCC, CrO3, CrO3/H2SO4 (Jone’s reagent)

Importat reducing agents

LiAlH4, NaBH4

What makes a good nucleophile

• Charge: negative charge

• Electronegativity: low electronegativity

• increases right and down

What makes a good electrophile

• Charge: positive charge

• Electronegativity: high electronegativity

• increases left and up

Ether layer

Non polar product

Aqueous layer

Polar product

What is true about resistors and capacitors in parallel?

They share the same voltage

How to add resistors in parallel

Use the inverse

How to add resistors in series

Use the normal sum