CHEM 1120 Edition 1nd Lecture 18 Outline of Last Lecture I Titrations a Acid Base indicators II Solubility Equilibria a Ksp III Factors affecting solubility a Common ion effect b pH c Complex ion formation d Amphoterism IV Precipitation and Separation of Ions Outline of Current Lecture I Classes of elements a Metals b Metalloids c Nonmetals II Properties of Nonmetals III Review of Periodic properties a Ionization Energy b Electron Affinity c Electronegativity d Atomic Radii e Periodic Trends IV Group 1A Hydrogen a 3 isotopes b 3 types of hydrogen chemistry c Properties of hydrogen d Hydrogen production V Noble Gases Group 8A a Least reactive group Current Lecture I II Chapter 22 Chemistry of Nonmetals Classes of elements a Metals These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III IV V i Majority of table ii Good conductors iii Mostly positive oxidation numbers iv Except for Hg solids in their standard state b Metalloids i Properties of both metals and non metals ii Many are semiconductors B Si Ge As 1 Need a certain voltage to conduct electricity c Nonmetals i Properties more diverse than metals ii Poor conductors iii Both positive and negative oxidation numbers iv H2 O2 N2 F2 Cl2 noble elements are gases at standard state v Br2 is a liquid all others are solids Properties of nonmetals a Only 17 114 are nonmetallic life based on non metallic elements b Negative oxidation states when combined with metals can have positive oxidation states in bonding to other non metals c Higher electronegativity s than metals d Nonmetals oxides are acidic combine with H2O to give oxy acids Review of periodic properties a Ionization Energy i Minimum energy needed to remove an electron from a gaseous atom or ion endothermic ii A A eiii Increases bottom to top left to right b Electron affinity i Negative of enthalpy for electron gain by atom smaller than IE ii Exothermic except for noble gases iii Ag e Ac Electronegativity i Tendency of an atom to gain additional electron density while retaining its original electron density ii Increases left to right bottom to top d Atomic radii i Increases right to left top to bottom Noble gases large ii Make atom negative size increases iii Make atom positive size decreases e Periodic Trends i Within a group smaller atoms are more likely to form pi bonds because they can get closer to other atoms Group 1A Hydrogen a Very common but unique Makes up VI i 75 of mass of universe 90 of atoms ii 11 of mass of oceans iii About 15 of mass of earth s crust iv 0 4 of mass of atmosphere v 9 5 of mass of human body b Three Isotopes i 1H protium ii 2h deuterium iii 3H tritium 12 3 year half life c Does not really belong to any group i Only element with an unfilled 1s valence shell that can either gain or lose an electron ii Hydride H very strong base d Hydrogen chemisty 3 types i Ionic hydrides Mg H2 MgH2 ii Metallic hydrides interstitial hydrides iii Covalent hydrides organic compounds are covalent hydrides e Properties of Hydrogen i Very large bond enthalpies ii Forms strong bonds with other elements exothermic iii It forms H bonds with electronegative O F and N strong intermolecular forces f Hydrogen Fuel cells i 2 H2 02 2 H20 ii Reaction is highly exothermic iii Water is only product iv Problem how will we make the H2 g Hydrogen Production i Commercially produced from reaction of methane with steam at 1100 degrees Celsius or carbon and steam ii Its production from the electrolysis of water is not energy efficient h Hydrogenation i Addition of dihydrogen to multiple bonds usually C double or triple bonded to C Noble Gases Group 8A a Extremely stable and unreactive b Liquid He boiling point 4 2 K is used as a coolant c Ne is used in electric signs d Ar is used in light bulbs and as an insulating gas between panes in thermal windows e Least reactive group Higher IE i Called inert until 1962 with discovery of Xe PtF6ii Many noble gas compounds include Xe and Kr iii He and Ne compounds unknown iv Helium is 2nd most abundant element in universe v