Chemistry Unit 3: Atomic Mass, Moles, Mass Spec + Percent Comp, Empirical & Molecular Formulas + Chemical Reactions + Stoich

atomic mass

a weighted average of isotopes that occur in nature

avagadro’s #

6.02 × 10²³

abundance

Average atomic mass = (Mass₁)(x) + (Mass₂)(1-x)

x is the decimal abundance of mass 1

percent composition

(by mass) part/whole x 100

empirical formula

simplest formula, shows ratio of elements

molecular formula

shows actual # of atoms in each element in a compound

steps to find empirical formula

percent to mass

mass to mole

divide by small

multiply till whole

steps to find molecular formula

find empirical formula

find mass of empirical formula

divide molar mass by empirical mass

reactants

left side of reactions, what is reacting

products

right side of reaction, what is produced

combustion

makes CO₂ and H₂O

synthesis

combining smaller elements to make a larger one

decompostion

breaking apart of a compound into smaller compounds/elements

single displacement

one element trades places with an element in a compound

double displacement

the cations and anions of two ionic compounds switch

equation necessary

balanced equation

limiting reactant

determines how much product can be formed

reactant in excess

chemical that has some leftover

theoretical yield

max amount of product that can be made

how many calculations necessary for theoretical yield/limiting reactant problems

2 stoich calculations

percent yield

(actual yield/theoretical yield) x 100