1. Unit 1: Stoichiometry and Gases By Alex and Maria

2. Tour of the Periodic Table –Groups and Periods Groups: vertical columns of elements with similar chemical and physical properties Periods: Horizontal columns

3. Element Groups Groups 1A: Alkali Metals Group 2A: Alkali Earth Metals Group 3A-4A: unnamed Group 5A: Pnictogens Group 6A: Chalcogens Group 7A: Halogens (salt) Group 8A: Noble Gases

4. Naming Ionic Compounds -Ide-Ite-AtePer…AteHypo- Monatomic NO 2 - NO 3 - Exceptions ClO 2 - ClO 3 - ClO 4 - ClO - OH - SO 3 - SO 4 2- CN - An ionic compound is a metal cation bonding to a non-metal anion Binary compounds are two nonmetal compounds, like NF3 (add prefix)

5. Protons, Neutrons, Electrons and Isotopes An Isotope is an atom with the same atomic number but different mass numbers because of a difference in the number of neutrons. The atomic number of an element is the number of protons Neutrons and Protons add up to the mass number of an ion/element The number of electrons is determined by the charge of the ion

6. Example Element Atomic # Mass # # of Protons # of Neutrons # of Electrons Na1123 Na + 1123 Na1124 11 12 13 1112 11 1011

7. Percent Abundance Percent Abundance is the percentage of atoms of each isotope in a sample % abundance= (# of atoms of given isotope) x 100% (total # of atoms of all isotopes of that element)

8. Mass Mole Relationships/Percent Composition Mass to Mole Relationships: Mass of AMoles of AMoles of BMass of B Percent Composition= (M A /M T ) x 100%

9. Empirical and Molecular Formula Empirical Formula: (HINT-Assume 100g sample) = % composition ÷ (Smallest number of moles) molar mass Molecular Formula: (M exp /M emp ) x (Elements in Compound)

10. Example (Empirical Formula) You have a compound composed of 49.8% C, 5.15% H, 16.49% O, and 28.87% N. Find the empirical formula 49.48g C x 1 mol C = 4.120mol C = 4 mol C 12.011g C1.031 5.15g H x 1 mol H = 5.110 mol H = 5 mol H 1.0079g H1.031 16.49g O x 1 mol O = 1.031 mol O = 1 mol O 15.9994g O 1.031 28.87g N x 1 mol N = 2.061 mol N = 2 mol N 14.0067g N 1.031 C 4 H 5 ON 2

11. Example (Molecular Formula) If the molar mass for the previous compound is 194.2 g/mol, what is its molecular formula? Theoretical molar mass = 4(12.011 g/mol C) + 5(1.0079 g/mol H) + (15.9994 g/mol O) + 2(14.0067 g/mol N) = 97.0963 g/mol 194.2 g/mol ~ 2 96.0963 g/mol 2(C 4 H 5 ON 2 ) = C 8 H 10 O 2 N 4

12. Balancing Reaction Equations/ Stoichiometry To balance a reaction equation be sure to have the same number of elements on the reactant and products side. See mass to mole relationship for stoichiometry.

13. Limiting Reactants/ Percent Yield Using stoichiometry find which reactant produces less of either product. This reactant is the limiting reactant. (M exp /M theor ) x 100%

14. Hydrates Hydrates are compounds which molecules of water are associated with the ions of the compound. There is no simple way to predict how much water will be present in a hydrate compound; it must be determined experimentally. Mass of Water=Mass of Hydrate Compound – Mass of anhydrous compound

15. Partial Pressure Partial pressure: P A =χ A P Total P total =((n A +n b +n c …)RT)/V χ A = n a /n total Mole fraction: Ratio of the number of moles of one substance to the total number of moles in a mixture of substances

16. Ideal Gas Law PV = nRT P = Pressure (atm) 1atm = 760torr = 760mmHg V = Volume (L) N = # of moles R = Rate =.08206 (L∙atm/mol∙K) T = Temperature (K) K =°C + 273K m/v = (PM)/(RT) = ρ GAS….

17. Kinetic Molecular Theory Tiny particles surrounded by much empty space Constantly moving Energy (speed 2 ) proportional to temperature (T) in Kelvin Particles collide without losing energy (preferably an elastic collision)

18. R.M.S speed/Effusion/Diffusion √(3RT)/M = √u2 R= 8.314 J/mol∙K (J=kg∙m2/sec2) T = Temperature (K) M = Molar Mass (kg/mol) Effusion is going from a container into a vacuum Diffusion is the mixing of two gases rate1/rate2= √M2/M1

19. Non-Ideal Gas Law (Van der Waals) (P real +a(n/v) 2 )(V real -bn)=nRT a= Attractive forces (atm∙L 2 /mol 2 ) b= Molecular volume (L/mol) a(n/v) 2 is the correction for intermolecular forces bn is the correction for molecular volume a and b are Van der Waals constants GAS!