General Review Atoms, Molecules Moles Isotopes: are atoms with the same of protons but different of neutrons, therefore, giving it a different mass . They are used for carbon dating, medical imaging, determining how drugs are metabolized, and used for smoke detectors. The mass on the periodical table is the sum of all the isotope masses. Ions: an atom that loses 1 or more electrons has a positive charge and is called a cation. An atom that gains 1 or more elections has a negative charge and is called an anion. Avogadros : 6.02x 10 23 number of moles x N = aumber of particles (atoms, molecules, ions) 21 Ex: A sample of glucose contains 2.58x10 molecules. Determine the of moles of glucose in the sample n= molecules N =a2.58x10 molecules 6.02x10 molecules mol = 0.00429 mol Molecular Mass: n(mol) = m(g)MM(gmol ) 1 Mass : mass = mass of 1 speciestotal mass of sample x 100 Mole Fraction: mole fraction= of moles of 1 species total of moles Mole : mole = of moles of 1 species total of moles x 100 Average molar mass: MM= (X x MM A + (X A MM ) B (X x MB ), wCere X iC the moles Araction of A, X B is the mole fraction of B. Solutions Molarity: concentration= molesvolume [c]=nV Dilution of a Solution: M 1 =1 V 2 2 3 Density of a Solution: density= massvolume, measured gml, lcgm , lcgL 1 Ex: Density of seawater is 1.029gml . What volume of 1.000kg of seawater? 1kg= 1000g V=mD= 1000g 1.092= 971.8mL PPM PPB: another method of expressing  involving only the masses of the solute and the solvent. 6 9 PPM is mass of solute mass of solution X 10 PPB is mass of solute mass of solution X 10 Reaction Stoichiometry Stoichiometry: quantitative relationships between reactants and products in a balanced chemical reaction. Percent Yield: yield= actual yield theoretical yield X 100 Limiting Reagent: the reagent whose amount is not enough to react completely with all the other reagents, determined by stoichiometry.