Stoichiometry & Gases By Alex Dorn & Georgia Kozonis

THE PERIODIC TABLE

MOLECULES & IONS Molecular Compounds – compounds that consist of discrete molecules at the particulate level. Ionic Compounds – compounds that consist of atoms that bear a positive or negative charge. Cations – metal atoms that generally lose one or more electrons in the course of reactions to form ions with a positive charge. Anions – nonmetal atoms gain one or more electrons to form ions with a negative charge in the course of their reactions. Monatomic Ions – single atoms that have lost or gained electrons. Valence Electrons – electrons in the outermost shell. Polyatomic Ions – contains two or more atoms, and the aggregate bears an electric charge.

RADIOACTIVITY Radioactivity – atoms of certain substances disintegrate when they emit alpha, beta, and gamma rays.

PROTONS, NEUTRONS, ELECTRONS & ISOTOPES Electrons – the fundamental particle of electricity. Protons – the fundamental, positively charged particle of atomic structure. Neutrons – particle with no electric charge. It is x 10^(-24) grams greater than the mass of a proton. Isotopes – atoms with the same atomic number but different mass numbers.

Mass Mole – the amount of substance that contains as many elementary entities (atoms, molecules, or other particles) as there are atoms in exactly 12 g of the carbon-12 isotope. 1 mole = x 10^23 particles (Avogadro’s number) Molar Mass - grams/moles Empirical Formula – when the atom ratio is the simplest. Molecular Formula – shows the true number of atoms of each kind of molecule.

LIMITING REACTANTS & YIELDS Step 1: Calculate the moles of reactants in use. Step 2: Decide which reactant is the limiting one. (Based on moles) Step 3: Use the limiting reactant to calculate the quantity of the product in question. Theoretical Yield – the maximum quantity of product that can be obtained from a chemical reaction. Actual Yield – the quantity of product obtained from a chemical reaction. Percent Yield = (actual yield/theoretical yield) x 100%

GAS EQUATIONS 1 standard atmosphere = 1 atm = 760 mm Hg 1 Pascal (Pa) = 1 Newton/meter^2 1 atm = 760 mm Hg = x 10^3 Pa = kPa 1 atm = bar Boyles Law – P1V1 = P2V2 Charles Law – V1/T1 = V2/T2 The General Gas Law – P1V1/T1 = P2V2/T2 The Ideal Gas Law – PV=nRT R=( atm)( L) = (L x atm) ( mol)( K) (K x mol) Note: All information used in equation is at standard. Density – d = m/V = PM/RT Partial Pressure – P(Partial)=X(Mole Fraction)P(Pressure)

KINETIC MOLECULAR THEORY Kinetic Energy Equation: KE = ½ (mass)(speed)^2 = ½ mu^2 When a line is placed over KE it represents average kinetic energy. Intermolecular Forces – the formation of a liquid or solid from a gas is evidence for the existence of forces of attraction between molecules. Kinetic-Molecular Theory: –Gases Consist of molecules whose separation is much greater than the size of the molecules themselves. –The molecules of a gas are in continual, random, and rapid motion. –The average kinetic energy of gas molecules is proportional to the gas temperature. –Gas Molecules Collide with one another and with the walls of their container, but they do so without loss of energy.

MOLECULAR SPEED In order to figure out RMS speed you must use the equation:  u 2 =  3RT/M