Periodic Properties: Groups 5A, 6A, and 7A A.Group 5A 1.Elements and SymbolsElement TypeState a.N = NitrogenNon-metaldiatomicgas b.P = PhosphorousNon-metalsolid c.As = Arsenic Metalloidsolid d.Sb = AntimonyMetalloidsolid e.Bi = BismuthMetalsolid 2.Some chemistry of the non-metal Group 5A Elements a.The elements tend to react to gain 3 electrons to be like noble gas b.These elements react with oxygen to form acidic compounds -HNO 3 = Nitric AcidH 3 PO 4 = Phosphoric Acid -P 4 (s) + 5 O 2 (g) -----> P 4 O 10 (s) -P 4 O 10 (s) + 6 H 2 O -----> 4 H 3 PO 4 (aq) c.Important Biological Elements -N is a component of every amino acid (protein) and DNA -P is a component of DNA

d.Phosphorous has more than one allotrope -Allotrope = stable solid phase -P 4 (s) is called “white phosphorous” is tetrahedral, and burns in air -P red is called “red phosphorous” and is made of chains of P 4 tetrahedra -P black is called “black phosphorous” and is a crystalline solid e.We will be reacting Red Phosphorous with Oxygen today in lab -Don’t bother with the bottle -Burn the phosphorous in the bunsen burner in the hood -Have a distilled water dampened piece of pH paper ready -Put the pH paper (green when damp) in the phosphorous smoke -If it turns red, that indicates the formation of acid -DON’T PUT HOT COMBUSTION SPOON INTO BOTTLE!!!

B.Group 6A 1.Elements and SymbolsElement TypeState a.O = OxygenNon-metaldiatomicgas b.S = SulfurNon-metalsolid c.Se = Selenium Non-metalsolid d.Te = TelluriumMetalloidsolid e.Po = PoloniumMetalloidsolid 2.Some chemistry of the non-metal Group 5A Elements a.The elements tend to react to gain 2 electrons to be like noble gas b.20% of the atmosphere and 50% of the crust is O (by mass) c.These elements react with oxygen to form acidic compounds d.Sulfuric Acid (H 2 SO 4 ) is the largest volume chemical used in industry -S(s) + O 2 (g) -----> SO 2 (g) -SO 2 (g) + H 2 O(l) -----> H 2 SO 3 (aq) = sulfurous acid e.We will be burning S(s) in the hood to produce H 2 SO 3 -Use same procedure as for phosphorous -All waste P and S should be completely burned off of the spoon

f.Sulfur has more than one Allotrope -Two allotropes of solid sulfur have 8-membered rings, but different crystal forms: “monoclinic” and “rhombic” -If liquid sulfur is cooled quickly, it solidifies as chains of sulfur atoms called “plastic sulfur” monoclinic rhombicplastic

C.Group 7A = Halogens (kJ/mol) 1. ElementsElement TypeStateE.A. a.F = FluorineNon-metaldiatomicgas, yellow-328 b.Cl = ChlorineNon-metaldiatomicgas, yellow-349 c.Br = Bromine Non-metaldiatomic liquid, brown-325 d.I = IodineNon-metal diatomic solid, purple-295 e.At = AstatineNon-metal radioactive solid 2.The chemistry of these elements is dominated by their need to add one e - 2 Na(s) + Cl 2 (g) -----> 2 NaCl(s) + large amount of heat Sodium Reacts Violently with Chlorine

3.Electron Affinity = energy given off when a gaseous element gains an e - a.X(g) + e > X - (g) b.Exothermic process because all elements accept e - due to + nucleus c.Adding e - is less favored down a group due to distance from nucleus d.Fluorine is so small, that repulsion from other electrons lowers its E.A. 4.Halogens with more favorable E.A. can take electrons from other halides a. Cl Br > 2 Cl - + Br 2 b.E.A: c.Cl 2 is reduced; Br - is oxidized 5.We will be studying this kind of reaction today in lab a.Prepare control samples: -I 2 /H 2 O + toluene = purple color of I 2 in toluene -Br 2 /H 2 O + toluene = orange color of Br 2 in toluene -Cl 2 /H 2 O + toluene = yellow color of Cl 2 in toluene Cl 2 Br 2 I2I2

b.Run all possible combinations of reactions between Cl/Br/I and observe the color of the toluene when finished Cl 2 + Br > yellow (Cl 2 ) if no reaction; orange (Br 2 ) if reaction Cl 2 + I > Br 2 + Cl > Br 2 + I > orange (Br 2 ) if no reaction; purple (I 2 ) if reaction I 2 + Cl > I 2 + Br > c.Use parafilm to cover test tubes to shake them up d.All halogen reactions go into a waste beaker in the hood

Incident: HF and Trifluoroacetic Acid Burn Incident: HF Exposure