AP Chemistry year review

matter

any substance that has mass and occupies space

atoms

the fundamental unit of matter, and the smallest unit that retains all the properties of an element

molecules

group of atoms that are bonded together to form a chemical compound

mole

international standard unit of measure for the number of molecules in a substance

Avogadro’s Number

6.022 × 10²³

# of moles

weight in grams / molar mass

of moles of substance

(# of moles in substance) x (Avogadro’s number)

mass spectroscopy

abundance of different atoms in a sample

mass spectrometer

separates molecules in a sample based on their charge & weight

Pure Substances

single type of substance that has consistent characteristics and cannot be broken down further through physical processes

element

pure substance that is made of a single type of atom

Compound

pure substance made of only one type of molecule

law of definite proportions

pure chemical compound broken down into elements always contains elements of a fixed ratio, independent of where and how it was created

mixture

made of more than one type of element or compound

homogenous

all parts of the mixture are identical to other parts due to even distribution of compounds

heterogenous

non-uniform distribution of compounds

protons

small subatomic positive particles

electrons

small negative charged subatomic particles

Neutrons

Smaller neutral subatomic particles

Mass number

whole number equal to the number of protons & neutrons of an element

Atomic Number

number of protons in the nucleus

isotopes

atoms with the same number protons but different number of neutrons

atomic mass

average mass number of all the atoms of that element

Anion

addition of an electron to an atom

cation

loss of electron of an atom

subshells are labeled

s, p, d, f, g, h

Aufbau principle

electrons fill the lowest energy orbitals first

Hund’s rule

electrons fill all orbitals of equal energy with one electron before pairing electrons

Pauli’s Exclusion Principle

two electrons of the same spin cannot occupy the same orbital; single orbital can only have one spin up and one spin down electron

Ionization energy

energy that is needed to remove an electron from an atom

Coulomb’s Law

calculate ionization energy, or energy needed to move