CHEM/PHYS: Miles Down High Yield MCAT (Lazy MCAT)

Rutherford Model

1911. Electrons surround a nucleus.

Bohr Model

- 1913. Described orbits in more detail.

-Farther orbits = increases Energy

- Photon emitted when n decreases, absorbed when n increases (AHED)

AHED

- Absorb light

- Higher potential

- Excited

- Distant from nucleus

Heisenberg Uncertainty

It is impossible to know the momentum and position simultaneously.

Hund's Rule

electrons only double up in orbitals if all orbitals first have 1 electrons

Pauli Exclusion Principle

Paired electron must be + 1/2 , − 1/2 .

Aufbau Principle

An electron occupies the lowest-energy orbital that can receive it

Avogadro's Number

6.0 x 10^23 = 1 mol

Planck's (h)

6.6x10^-34 J•s

Speed of Light (c)

3.0 × 10^8 m/s

Light Energy

- E = hc/λ

- E = hf

Diamagnetic

All electron pairs are REPELLED by an external magnetic field

- Ex: He = 1s^2

Paramagnetic

1 or more unpaired electrons PULLED into an external magnetic field

- ex: C = 1s^2, 2s^2, 2p^2

n

- Principal

- electron energy level or shell number

- values: 1, 2, 3.......

l

3D shape of orbital

- Values: 0, 1, 2, n-1

Numbers based on Orbitals

- 0 = s orbital

- 1 = p orbital

- 2 = d orbital

- 3 = f orbital

- 4 = g orbital

ml

Orbital sub-type

- Values: -l to +l

ms

Electron spin

- Values: +1/2, -1/2 (Pauli Exclusion Principal)

2n^2

Maximum electrons in terms of n

4l + 2

Maximum electrons in subshell

Free Radical

An atom or molecule with an unpaired electron.

Non-metals

H, C, N, O , P, S, Se

(Se C.H.O.N.P.S)

Noble Gases

He, Ne, Ar, Kr, Xe, Rn

- end of periodic table

Halogens

F, Cl, Br, I, At, Ts

- column before noble gases

- non-metal

Mettaloids

B, Si, Ge, As, Sb, Te, Po

- staircase

Alkali Metals

Li, Na, K, Rb, Cs, Fr

- 1st column; all except H

Alkaline Earth Metals

Be, Mg, Ca, Sr, Ba, Ra

- 2nd column

Zeff (Effective Nuclear Charge)

- Pull between nucleus & valence electrons

- Increase going up & to the right

- Ex: F

IE (Ionization Energy)

- Amount of energy required to remove an electron from an atom

- Increases going up & to the right

EA (Electron Affinity)

- Gain electron

- Positive value

- Noble Gases have none

- Ex: F

Electronegativity

- Force exerted on an electron in a common bond

- Kr & Xe are the only noble gases that have it.

- Increases going up & to the right

- Ex: F

Common Electronegativities

H = 2.0

C = 2.5

N = 3.0

O = 3.5

F = 4.0

Atomic Radius

- Increases as you go down, decreases as you go left (only oppositie of them)

- Ex: Fr

Intermolecular Forces

- Hydrogen (O-H, N-H, F-H)

- Dipole-Dipole

- London Dispersion

-- Increases as you go up

Van de Waals

- weak attractions between non polar molecules

- includes dipole-dipoles & London dispersion forces

Dipole-Dipole

attractions between oppositely charged regions of polar molecules

London Dispersion

- resulting from the constant motion of electrons and the creation of instantaneous dipoles

- weakest intermolecular force

Combination

Two or more reactants forming one product

Decomposition

Single reactant breaks down

Combustion

Involves a fuel, usually a hydrocarbon, and O2 (g). Commonly forms CO2 and H2O.

Single Displacement

An atom or ion in a compound is replaced by another atom or ion.

Double-Displacement: (metathesis)

Elements from two compounds swap places.

Neutralization Reaction

reaction of an acid and a base to form a neutral solution of water and a salt

Hydrolysis

Using water to break the bonds in a molecule.

Radioactive Decay

The loss of small particles from the nucleus.

Arrhenius

- k = rate constant

- A = frequency factor

- Ea = activation energy

- R = gas constant = 8.314 J/molK

- T = temp in K

Bicarbonate Buffer

- increase pH = lower respiration, trapping CO2

- decrease pH = increase respiration to blow off CO2

Standard Conditions

298 K, 1 atm, 1M, 273K (0°C)

Fusion

solid to liquid

Sublimation

solid to gas

Deposition

gas to solid

Hess' Law

Enthalpy changes are additive.

ΔH°rxn from heat of formations

∆H°rxn = ∆H°products − ∆H°reactants

ΔH°rxn from bond dissociation energies

∆H°rxn = ∆H°reactants - ∆H°products

Entropy Equation

ΔS = qrev/T

Ideal Gas

- Theoretical gas whose molecules occupy negligible space and whose collisions are perfectly elastic.

- Gases behave ideally under reasonably increasing temperatures and decreasing pressures.

1 mol Gas

22.4 L

1 atm

760 mmHg = 760 torr = 101.3 Pa = 14.7 psi

Ideal Gas Law

- PV=nRT

- R = 8.314 J/mol K

Density of Gas

PM/RT

Diatomic Gases

H2, N2, O2, F2, Cl2, Br2, I2

- Have No Fear Of Ice Cold Beer

Dilutions

M1V1=M2V2

Soluble

- Na+, K+, NH4+, NO3-

- Cl-, Br-, I-

- SO4^2-

Insoluble

S2-, O2-, OH-, CrO4-^2, PO4^3-, CO3^2-

Fluids

- Substances that flow and conform to the shape of their containers, includes liquids and gases.

- They can exert perpendicular forces but not shear forces.

Solids

- Do not flow.

- They maintain their shape regardless of their container

Density

- Mass per unit volume of substance

- p = m/v

Pressure

- A measure of force per unit area; it is exerted by a fluid on the walls of its container and on objects placed in the fluid. Scalar quantity.

- The pressure exerted by a gas on its container will always be perpendicular to the container walls.

- P = F/A

Absolute Pressure

- The sum of all pressures at a certain point within a fluid; it is equal to the pressure at the surface of the fluid plus the pressure due to the fluid itself.

- Ptotal = P0 + pgh

* In water, every additional 10m of depth adds » 1 atm to Ptotal

Gauge Pressure

- The difference between absolute pressure and atmospheric pressure.

- In liquids, gauge pressure is caused by the weight of the liquid above the point of measurement.

- Pgauge = P - Patm = (P0 + pgz) - Patm

Pascal's Principle

- A pressure applied to an incompressible fluid will be distributed undiminished throughout the entire volume of the fluid.

- P = F1/A1 = F2/A2

Hydraulic Machines

Operate based on the application of Pascal's principle to generate mechanical advantage.

Archimedes' Principle

- When an object is placed in a fluid, the fluid generates a buoyant force against the object that is equal to the weight of the fluid displaced by the object.

- FB = pvg

- m = pV

- F = PA

Specific Gravity

- Ratio of density of an object to density of water.

- P object/P water

Cohesive vs. Adhesive

Fluids experience cohesive forces with other molecules of the same fluid and adhesive forces with other materials.

Surface Tension

Cohesive forces give rise to surface tension.

Viscosity

- A measure of a fluid's internal friction.

- Viscous Drag is a nonconservative force generated by viscosity.

Laminar Flow

Smooth and orderly.

Turbulent Flow

Rough and disorderly.

Poiseuille's Law

Determines the rate of laminar flow

Flow Rate

- Q = vol/time = Av

- A = cross sectional area

- v = velocity

Continuity Equation:

- Fluids will flow more quickly through narrow passages and more slowly through wider ones.

- Q = v1(A1) = v2(A2)

Bernoulli's Equation

The sum of the static pressure and the dynamic pressure will be constant between any two points in a closed system.

Venturi Effect

The VELOCITY of a fluid passing through a constricted area will INCREASE and its static PRESSURE will DECREASE

Venturi Tube

- The average height of the horizontal tube remains constant, so pgh remains constant at points 1 and 2.

- As cross-sectional area decreases from point 1 to point 2, the linear speed must increase.

- As the dynamic pressure increases, the absolute pressure must decrease at point 2, causing the column of fluid sticking up from the Venturi tube be to be lower at point 2.

Circulatory System

- The circulatory system behaves as a closed system with nonconstant flow.

- The nonconstant flow = our pulse.

Circulatory System Equations

- v = Q/A = cardiac output/cross - sectional area

- Q = vA

- P = Q x R = cardiac output x resistance

- P = vAR

Breathing

Inspiration and expiration create a pressure gradient not only for the respiration system, but for the circulatory system too.

Alveoli

Air at the alveoli has essentially zero speed.

Arrhenius Acid

Produces H+ (same definition as Brønsted acid)

Arrhenius Base

Produces OH-

Brønsted-Lowry Acid

Donates H+ (same definition as Arrhenius acid)

Brønsted-Lowry Base

Accepts H+

Lewis Acid

Accepts electron pair

Lewis Base

Donates electron pair

Amphoteric Species

- Species that can behave as an acid or a base.

- Amphiprotic = amphoteric species that specifically can behave as a BrønstedLowry acid/base.

Polyprotic Acid

An acid with multiple ionizable H atoms.

Water Dissociation Constant

- Kw = 10^-14 at 298K

- Kw = Ka x Kb

pH and pOH

- pH = -log[H+]

- pOH = -log[OH-]

- pH + pOH = 14

- [H+] = 10^-pH

P Scale Value Approximation

- −log (A × 10^-B)

- p value ≈ −(B + 0.A)