AP Chemistry Ultimate Guide

electrostatic force

attraction between opposite charges and the strength can vary depending on how far the charges are from each other.

subshell

shape of the space an electron can be found in

ionization energy

the energy an atom must absorb to eject an electron

aufbau principle

electrons must fill up orbitals, subshells, and shells in order of increasing energy.

electromagnetic radiation

electrons can jump to higher energy levels when absorbing this energy

Bohr model

demonstrates the electron organization of an atom

avogadro’s number

number of atoms in a single mole of any given element

anions

have an overall negative charge

cations

have an overall positive charge

electronegativity

how much an element attracts electrons to it’s nucleus

molarity (M)

expresses the concentration of a solution in terms of volume

Coulomb’s law

the closer an electron is to the nucleus, the stronger the attraction and the less potential energy there is

valence electrons

electrons in the outermost shell

photoelectron spectrum

graph of the ionization energies for all electrons when ejected from the nucleus.

electrons

have significantly less mass than protons and neutrons and do not contribute to the mass.

isotopes

atoms of an element with different numbers of neutrons, but same amount of protons.

percent compostition

percent by mass of each element in a compound.

substitutional alloys

a molecule with a similar radius replaces a metal atom

potential energy

stored, motionless energy

kinetic energy

energy in motion

covalent bond

between two nonmetals

metallic bond

between two metals

ionic bond

between a metal and nonmetal

interstitial alloy

an atom with a smaller radii fills the space between metal atoms with larger radii

network covalent bonds

strongest bond, held together in lattice structure

sea of electrons

electron organization for metallic bonds

resonance form

different yet equally likely forms of a molecule’s structure f

formal charge

the most likely version of a lewis dot structure to form

molecular geometry

three-dimensional structure of a molecules arrangement

london dispersion forces (LDFs)

IMF between all molecules, very weak attraction, caused by random electron movements

dipoles

oppositely charged ends of a molcule

effusion

the rate at which a gas will escape a pin-sized hole from high to low pressure

polar covalent bonds

an unequal share of electrons

nonpolar covalent bonds

equally shared electrons

dipole-dipole forces

IMF that occurs when a positive dipole of a molecule is attracted to the negative dipole of another molecule

hydrogen bond

IMF between hydrogen and oxygen, nitrogen, or fluorine

acid

a compound that can donate a proton

base

compound capable of accepting a proton

amphoteric

a compound that can behave as both an acid or a base

catalyst

a substance that speeds up a reaction rate

intermediate

a substance created in one elementary step and used up in another

half-life

how long it takes for half of a substance to decompose

activation energy

energy required for a reaction to start/occur

exothermic

when energy is transferred from system to surroundings (beaker feels hot)

endothermic

heat transfers from surroundings to system (beaker feels cold)

when bonds are formed, energy is ____

releasedw

when bonds are broken, energy is ____

absorbed

ΔH

enthalpy change

enthalpy

total heat content of a system (H)

enthalpy of formation

amount of energy released when one mole of a compound is produced from pure substances

reaction quotient, Q

the relative amount of products and reactants at any point in time

K

equilibrium constant

Le Chatelier’s Principle

when a stress is added to a reaction, the equation will change to adjust for the stress and return to equilibrium

common ion effect

when an element is added to a solution with a salt, the salt equilibrium will change if the element is similar to the salt

equilibrium reaction

reaction is reversible and constantly occurring with no change in concentrations of product or reactants

only ____ stress/change can change the equilibrium constant value

temperature

neutralization reactions

acid and base react, producing water and a salt

strong acid

dissolves completely in water

Kw value

1.0 x 10^-14

buffer solution

can resist pH change when small amounts of strong acid or base added

polyprotic acid

can give up more than one proton

equivalence point

just enough acid/base added to base/acid to neutralize

Gibbs Free Energy

G, determines thermodynamic favorability based on the entropy, enthalpy, and temperature

entropy

S, the disorder of a system, “chaos”

standard conditions

25 celsius, 1 atm, 1M

mass spectrometry

determine the average mass for different isotopes of a specific element

pauli exclusion principle

when two electrons fill up an orbital, they must spin in opposite directions: clockwise and counterclockwise.

hund’s rule

when electrons are filling the orbitals of the subshell, they will only have two in one orbital when it is not possible to have each electron in its own orbital.

noble gas

has all shells completely full of electrons

linear molecular geometry

two electron pairs

trigonal planar geometry

three electron pairs

tetrahedral electron geometry

four electron pairs

trigonal bipyramidal geometry

five electron pairs

octahedral geometry

six electron pairs

kinetic molecular theory

gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion.

kinetic molecular theory does not work at ____ temperature

low

kinetic molecular theory does not work at ____ pressure

high

absorbance

the amount of light that does not get through (gets absorbed) by a colored solution

gravimetric analysis

used to determine an unknown element in a precipitate reaction

hydrocarbon combustion

carbon + hydrogen (and sometimes oxygen) is ignited and produces CO2 and waters

synthesis reaction

when elements or simple compounds are combined to form a single, more complex compound.

redox reaction

electrons are swapped between reactants and the oxidation states of the reactants are changed.

decomposition reaction

opposite of synthesis- occurs usually in the presence of heat

precipitation reaction

two aqueous solutions mixing to create a solid precipitate.