FINALS: Chemistry

mole ratio

ratio of coefficients in balanced equation

theoretical yield

maximum amount of product that can be produced, answer when you have grams + grams

actual yield

the amount produced in the lab

percent yield

measure of how efficient a chemical reaction is, actual yield/theoretical yield x 100

energy

the ability do work or produce heat

thermodynamics

study of energy

potential energy

held within chemical bonds

kinetic energy

exhibited by moving particles

endothermic

energy absorbed, ex. ice cube melting

exothermic

energy is released, ex. fire burning

the first Law of Thermodynamics

energy is neither created nor destroyed

system

the part of the universe observed

surroundings

everything else in the universe

heat

a flow of energy due to a temp difference

q

heat energy in J

m

mass in grams

C

specific heat capacity in J/g °C 

ΔT

change is temperature, T_f - T_i

temperature

measure random motions of components of a substance

enthalpy

a measure of energy of a system, ΔH

electromagnetic energy

energy that travels as waves through space at a speed of light in a vacuum

wavelength

distance between two consecutive wave peaks, lil wave thing

frequency

number of wave peaks that pass a point per given time period, V

speed

how fast a given peak travels, C

wavelength unit

meters

frequency unit

hertz

speed unit

3.00 × 10⁸ m/s

orbital

3D region where there is high probability of finding an electron

principle energy level

discreet energy level of an atom

sublevel

part of principle energy level that corresponds to an electron orbital, indicated by a letter

number of electrons an orbital can hold

2

labeling orbitals

1. number of principle energy level

2. letter of sublevel

level 1

1s, one orbital

level 2

2s and 2p, 3 orbitals

level 3

3s, 3p, 3d, 5 orbitals

electron configuration

shows the arrangement of electrons in an atom

noble gas abbreviation

1. use noble gas on row directly above your element

2. put noble gas in brackets

3. continue configuration left - right same row as element

pauli exlcusion principle

orbitals can hold up to two electrons, those electrons must have opposite spins

valence electrons

electrons in the outermost principal energy level of an atom, the ones involved in making bonds

core electrons

inner electrons

nuclear attractive force

stronger when electrons are closer

atomic size (radius)

distance between the nucleus and the edge of the electron cloud

atomic size trend

decreases across a row, increases down a group

ionization energy

the amount of energy required to remove an electron

ionization energy trend

opposite of atomic size, increases across a row and decreases down a group

energy is released by . . .

emitting light

these are carried by . . .

photons

quantized

energy of an atom can only exist in specific, discrete units

ground state

lowest possible energy state

excited state

atom exposed to energy source, excited to higher energy level

the Bohr model

only works for hydrogen atom, electrons do not orbit nucleus

the wave mechanical model

electrons in orbitals, not orbits, gives probability of where electrons could be

octet rule

atoms form bonds that give them 8 valence electrons

electronegativity

the ability of an atom to attract electrons while in a compound

bond polarity

the difference between the EN values of the atoms in a bond

below 0.4

nonpolar

0.4 - 1.7

polar

above 1.7

ionic

lone pair

unshared pair of electrons

duet rule

followed by hydrogen, most stable when surrounded by 2 electrons

what atoms go in the center?

first atom, carbon

what atoms don’t go in center?

hydrogen, halogens

steps for Lewis Structures

1. calculate total # of valence electrons

2. connect each atom with line

3. subtract those values from total

4. distribute remaining # to satisfy rules

resonance

when more than 1 valid Lewis Structure exists for a bond

for ions . . .

add an electron for each negative or subtract for each positive, add brackets with charge

VESPR model

1. electron pairs want to be as far from each other as possible

2. double bonds treated as one repulsive unit

3. 2 atoms are linear

pressure

force of all gas particle and wall collisions

vacuum

absence of pressure

pressure units

pascal (Pa), mmHg, torr, atm, psi

atmospheric pressure

caused by weight of air in atmosphere, measured by barometer

barometer

air pushes down on mercury, the more pressure there is, the higher the mercury rises in the tube

Boyle’s Law

pressure + volume have indirect relationship, P₁V₁ = P₂V₂

Charle’s Law

volume + temperature have a direct relationship, V₁/T₁ = V₂/T₂

Avogadro’s Law

volume + moles have a direct relationship, V₁/n₁ = V₂/n₂ ALSO 22.4 L = 1 mole

The Ideal Gas Law

PV = nRT

Dalton’s Law of Partial Pressures

total pressure of a mixture of gases is equal to sum of their pressures

characteristics of gases

1. no fixed volume

2. low density

3. mixtures are homogeneous

kinetic molecular theory

movement of particles in matter, attempts to explain ideal gas behavior

intramolecular forces

between atoms, chemical bonds

intermolecular forces

between molecules, keeps solids + liquids together

London Dispersion

nonpolar bonds, C + h, noble gases

Dipole-Dipole

polar bonds, ionic bonds

Hydrogen bonding

N, O, F

polarizability

ability of electron cloud to be unevenly distributed

number of atoms

stronger intermolecular forces, more attraction sites

relationship between atomic size/boiling point

larger atomic size causes higher boiling point

shape of molecule

more linear structure means more attraction sites

crystaline

regular microscopic arrangement

amorphous

disordered microscopic structure

ionic solids

made of ions, stable, high melting points

molecular solids

held together by weak intermolecular forces, lower melting points

metallic solids

held together by metallic bonds, “electron sea” model

alloids

homogeneous mixture of metals

solution

homogeneous mixture

solvent

dissolves other substances

solute

the substance being dissolved

soluble

able to dissolve in a particular solvent

insoluble

unable to dissolve in a particular solvent

miscible

liquids that dissolve in each other

immiscible

liquids that are insoluble in each other