NMAT Review: Chemistry

Ionic bonds

When one atom gives up an electron to an atom that wants to receive an electron.
-Atoms want to gain/lose electrons in their valence shells to look more like the noble gases.
-Afterwards, the atoms have charges. Negative, if they gained an electron, and p

Covalent bonds

When the atoms share electrons to fulfill their valence shell preferences.
-Depending on the electronegativity of each atom, there may be partial charges (ex. H2O)

Electronegativity

How badly it wants to hog electrons in a bond; the power of an atom in a molecule to attract electrons o itself

Electron Affinity

How much it wants electrons

Balancing equations

Make sure molecules are the same on both sides.
Tip: put an initial 1 in front of the most complex compound

Extensive vs. intensive property

Extensive - a property that changes when the size of the sample changes
Intensive - a property that DOESN'T change when the size changes

metathesis rxn

A reaction in which compounds exchange ions

redox rxn

A reaction in when there's an oxidation/reaction, or losing/gaining of an electron

Reduction vs. oxidation half-rxn

You can write a redox reaction as two half-reactions, one showing the reduction process, and one showing the oxidation process.
In a reduction half-rxn, the one being REDUCED is gaining the electron while the other compound causing the reduction is the RE

s, p, d, f orbitals

1, 2, 3... denote the energy level
s, p, d, f... denote the shape of the orbital
-these orbital shapes are around the x, y, z axes
How much each orbital holds (within each orbital is two electrons max):
s: 2 (1 spot)
p: 6 (3 spots)
d: 10 (5 spots)
f: 14 (

VSEPR shapes

Electron Configuration Notation

Use the electron filling pattern and the number of valence electrons of an element to figure out the notation. Fill in the amount of valence electrons, writing the number of electrons in each orbital energy level in superscript until you run out.

Bronsted-Lowry bases & acids

BL BASE is a proton DONOR
BL ACID is a proton ACCEPTOR

equilibrium constant K

Keq = [products]^coefficient / [reactants]^coefficient
To get the Keq of the reverse reaction, flip the equation
If K is large, then the products are favored.

Kp formula

An equilibrium constant like Keq, but instead deals with partial pressures of the gaseous compounds

IUPAC rules

1) Identify the longest carbon chain, this will be the parent chain
2) Start number ing the carbons on the end that will give the substituents the lowest number
3) When there is only one type of substituent and number more 2+, use the prefixes (di, tri, t

IUPAC substituents

Arrhenius equation

k = Ae^(-Ea/RT)
k - rate constant
A - frequency factor
Ea - Activation energy
R - Gas constant
T - temperature in Kelvin

Henderson-Hasselbach equation

pH = pKa - log([conjugate base]/[acid])

Henry's law

At a given temperature, the solubility of a gas (S) in a liquid is directly proportional to the pressure (P) of the gas above the liquid.
So as pressure of a gas increases, so does its solubility

Nuclear reactions (alpha, beta, gamma particles)

Nuclear reactions involve changes in the nucleus whereas chemical reactions involve a transfer of electrons.
nuclide symbolism: A/Z X
A - mass number (number of neutrons and protons)
Z - atomic number
X - elemental symbol
- alpha emission: Helium particle

pH equation

pH = -log [H+]
Take the log of the concentration of the hydronium ion.

pOH equation

pOH = -log [OH-]
Take the log of the concentration of the hydroxide ion.

Periodic table trends

Electron Affinity: increases from left to right & bottom to top
Ionization Energy: increases from left to right & bottom to top
Electronegativity: increases from left to right & bottom to top
Atomic Radius: increases from right to left & top to bottom
Met

Rate law and order reactions

Zero-order rate law: rate = k
-independent of the concentration of the compound, the rate is the same (horizontal straight line)
First-order rate law: rate = k[A]
-reaction that depends linearly on only one reaction (negative straight line)
Second-order r

Half life equations

Zero-order half-life: t(1/2) = [Ao]/2k
First-order half-life: t(1/2) = 0.693/k
Second-order half-life: t(1/2) = 1/k[Ao]

Gas law

PV = nRT
P - pressure
V - volume
n - number of moles
R - Gas constant
T - temperature

Gas constant R

0.0821 L
atm/mol
K OR
8.314 J/mol*K

Combined gas law

P1V1/T1 = P2V2/T2

Avogadro's constant

6.022 x 10^23

moles to grams

moles x grams/1 mole = grams of molecule
To get moles: 1 mole/grams x grams of molecule = number of moles

How do you know if a rxn is spontaneous or not?

Delta G = Delta H - (T)(Delta S)
Delta G - measure of free energy in the system (Gibbs Free Energy)
Delta H - measure of heat that is given off (-) or absorbed (+) by the environment (Enthalpy)
Delta S - measure of entropy of the system
T - temperature in

Endothermic vs exothermic graphs

In endothermic reactions, the products will have a higher potential energy. And since heat is absorbed, delta H is positive
In exothermic reactions, the products will have a lower potential energy. And since heat is expelled, delta H is negative.

Nernst equation

Allows us to calculate the cell potential under non-standard state conditions
E = E^o - (RT)lnQ/(NF)
OR if you plug in the constants and temperature at 298.15K (25C):
E = E^o - (0.0257)lnQ/n
E - instantaneous cell potential
E^o - instantaneous cell potent

Galvanic cells

When Delta G is negative, the redox reaction is still going and there is a voltage.
Delta G = Delta G^o + RTlnQ
Delta G - free energy
Delta G^o - free energy under standard conditions (-212kJ/mol)
R - Gas constant
T - temperature in Kelvin
Q - [products]/

Functional Groups

Alcohol: -OH
Ketone: O=C-R^2
Aldehyde: O=C-H
Carboxylic acid: O=C-OH
Ether: R-O-R
Amine: N-H^2-R

Molarity

concentration based on mol/Liter

Normality

grams solute / (amt. of solute (L) * equivalent weight)
equivalent weight = molecular weight/valence capacity

ortho vs para

cis vs trans

cis - groups are on the same side
trans - groups are criss-crossed