particles
generic term for individual molecules, formula units, or atoms(regardless of what is being counted)
formula unit
smallest amount of an ionic compound(ionic compounds= compound made up of all metals and nonmetals)
atom
generic term for individual elements
molecule
a covalent compound's smallest molecule (Covalent compound= compound made up of all nonmetals)
mole (mol)
the convenient unit expressing the amount of a substance (typically the mass on the periodic table or sextillion particles)
1 mole is the number of particles of substance that is contained in 12.0 grams of__________
carbon
The number of particles in a mole
6.02 X 10^23
How can we show that Avogadro's number is about 6.02 X 10^23?
by looking at the structure of a crystal
Molar Mass
amount of substance that contains Avogadro's number of particles (or the mass of one mol of a substance)
-generally stated in grams /1 mole
Avogadro's number is
6.02 X 10^23 (aka sextillion)
mole to mass(g) conversion
multiply by the molar mass of the compound
mass(g) to mole conversion
divide by molar mass of the compound
CONVERSION TIP
ALWAYS convert to moles if you aren't already starting there!
percent composition
the percentage by mass of each element in a compound
to calculate percent composition...
divide the mass of the specified element in the compound by the mass of the compound; then multiply by 100 to get a percentage
molecular formula
shows the exact number of each kind of atom (found in covalent compounds)
empirical formula
shows the lowest ratio of atoms in an ionic compound
for ionic compounds, the empirical formula is the same as...
the chemical formula
to calculate empirical formula:
1. Convert the mass of each element to moles
2. divide each moles by the smallest number of moles
(if they are .5, multiply ALL by 2)
3. These mini answers become the subscripts of each element in the compound
molecular formula
the actual formula of a molecular compound (a multiple of the lowest ratio)
to find molecular formula
Find the number of times the mass of the empirical formula mass will divide into the GIVEN mass; Whatever that multiple is, should be the number the subscripts in the empirical formula are multiplied by. molecular formula mass
stoichiometry
the numerical relationship that exists in chemical formulas and reactions
molar ratio
the coefficients that are used to balance chemical reactions
limiting reactant
the chemical that runs out first in the reaction and determines the amount of product that will be produced
excess reactant
the reactant that is left over
the reactant that produces the smallest amount of product is
the limiting reactant
percent yield
percent of the expected amount of product that was actually produced
to get percent yield:
divide the actual yield(amount produced in the lab) by the theoretical yield (calculations done with stoichiometry)