Chem 1120 1st Edition Lecture 21 Outline of Last Lecture I Noble Gases II Halogens III Oxygen Family Outline of Current Lecture I Other Group 6A Elements II Nitrogen Family III Allotropes Carbon Family Boron Family Current Lecture I Elements in Group 6A have oxidation states of 2 as well as several positive oxidation states and can have expanded octets S Sulfur brittle soft yellow solid with low melting point that facilitates its melting in rock with hot steam and transport to surface as emulsion Frasch process has a large oxidation number range 2 to 6 Organic compounds of sulfur Compounds with SH groups are called thiols have nasty intense odors Inorganic Sulfides also found in some protein active sites especially in electron transfer Iron Pyrite FeS is an inorganic sulfide pyrites contain the disulfide ion Disulfides are an important structural feature in proteins cysteine SH groups from different sites in the protein react to form S S bond that staples protein together improving stability Sulfur oxides oxyacids and oxyanions SO2 is a poison particularly to lower organisms it s used to sterilize dried fruit and wine by dissolving in water 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 Sulfuric acid is a versatile diprotic acid hot concentrated 98 sulfuric acid is a strong oxidizing agent and a strong acid used in production of phosphate fertilizer petroleum refining manufacture of detergents dyes other chemicals Selenium and Tellurium these elements are anions in minerals with Cu Pb Ag and Au they are naturally found as helical chains of atoms selenium is not electrically conductive in the dark but quite so in light II Nearly all compounds of the nitrogen family are covalent N and P are nonmetals and As and Sb are metalloids metallic Bi forms mostly covalent compounds Nitrogen N2 is the most common atmospheric element dinitrogen boils at 196 oC it creates a triple bond and is the most stable homonuclear diatomic molecule Ammonia N oxidation number 3 one of the most common N compounds by product of urea catabolism colorless gas with strong acrid odor acutely toxic as a liquid it is polar with strong H bonding Haber Bosch process uses catalysts and high P and high T for NH3 synthesis Dinitrogen fixation plants need N but most cannot fix N2 into usable form Blue green algae and symbiotic bacteria on roots of soybeans alfalfa and clover convert N2 to NH4 at standard T and P Most important oxides of N N2O NO NO2 III Phosphorous allotropes P4 P4O6 or P4O10 Phosphates used in many products toothpaste feritlizer rock etc Group 4A Carbon Family Carbon C is nonmetal forms covalent compounds Metalloids Silicon Si and Germanium Ge form strong polar covalent bonds silicon is very important in geochemistry electronics Metallic Tin Sn and Lead Pb exhibit 2 and 4 oxidation states Carbon has several allotropes graphite diamond fullerenes carbon nanotubes graphene buckyball Occurs in nature as carbonates coal petroleum and natural gas Carbides carbon combines with metals to form ionic carbides very reactive because the carbon prefers covalence Oxides of Carbon carbon monoxide carbon dioxide Cyanide C and N bound together with a triple bond very toxic isoelectronic with CO There are chains double chains sheets and framework silicates Silicones are synthetic polymers Chain sheet and framework silicones are produced commercially Glasses have amorphous non crystalline structures broad melting point ranges behave like supercooled liquids Group 3A Boron Family Metalloid Boron B forms covalent compounds common compounds include boric acid and borax Aluminum Al is a typical metal with compounds predominantly in the 3 oxidation state Gallium Ga Indium In and Thallium Tl poisonous exhibit 1 3 oxidation states Electron deficient boron compounds accept a pair of electrons from a donor many boron nitrogen compounds are analogous to C compounds Boranes boron hydrides have novel structures weirdly shaped