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Copyright McGraw-Hill 20091 Chapter 24 Nonmetallic Elements and Their Compounds Insert picture from First page of chapter
Copyright McGraw-Hill 20092 24.1 General Properties of Nonmetals Properties of nonmetals - more varied than those of metals Physical state –Gases: hydrogen, oxygen, nitrogen, fluorine, chlorine, and the noble gases –Liquid : bromine –Solids: All the remaining nonmetals Poor conductors of heat and electricity Exhibit either positive or negative oxidation numbers.
Copyright McGraw-Hill 20093 Metalloids - small group of elements have properties characteristic of both metals and nonmetals. More electronegative than metals Electronegativity increases from left to right across any period and from bottom to top in any group in the periodic table With the exception of hydrogen, the nonmetals are concentrated in the upper right-hand corner of the periodic table Compounds formed by a combination of metals with nonmetals tend to be ionic, having a metallic cation and a nonmetallic anion.
Copyright McGraw-Hill 20094 Nonmetals and Metalloids on the Periodic Table Nonmetals coded in blue and metalloids in orange..
Copyright McGraw-Hill 20095 24.2 Hydrogen Simplest known element Exists as a diatomic molecule H 2 is a colorless, odorless, and nonpoisonous gas. At 1 atm, boiling point is −252.9°C (20.3 K). Most abundant element in the universe
Copyright McGraw-Hill 20096 Ground-state electron configuration: 1s 1. –Resembles the alkali metals (Group 1A) in that it can be oxidized to the H + ion, which exists in aqueous solutions in the hydrated form. –Resembles the halogens (Group 7A) in that it forms the hydride H − (hydride ion) - isoelectronic with helium (1s 2 ) Found in a large number of covalent compounds. Unique capacity to form hydrogen bonds
Copyright McGraw-Hill 20098 Laboratory Generation of Hydrogen
Copyright McGraw-Hill 20099 Binary hydrides - compounds containing hydrogen and another element, either a metal or a nonmetal. Types of hydrides –Ionic hydrides direct combination of molecular hydrogen and any alkali or alkaline earth metal –Solids with high melting points –Contain the strong Br Ø nsted base, H −
Copyright McGraw-Hill 200910 –covalent hydrides - the hydrogen atom is covalently bonded to the atom of another element Types of covalent hydrides –Discrete unit structure – NH 3 –Polymeric structure – (BeH 2 ) x –Interstitial hydrides – compounds of hydrogen and transition metal in which the atomic ratio is not constant – titanium hydride ranges from TiH 1.8 to TiH 2.
Copyright McGraw-Hill 200911 Binary Hydrides of Representative Elements
Copyright McGraw-Hill 200912 Isotopes of hydrogen –Hydrogen has three naturally occurring isotopes –, hydrogen, (99.985%) –, deuterium, symbol D, (0.015%) –, tritium, symbol T, (radioactive, t 1/2 =12.5 years. –Deuterium containing water, D 2 O Called heavy water or deuterated water Toxic Affects reaction rates – isotopic effect
Copyright McGraw-Hill 200914 Hydrogenation - addition of hydrogen to compounds containing multiple bonds, usually carbon to carbon double or triple bonds. –Catalyzed by metals (Pt or Cd) –Important in food industry
Copyright McGraw-Hill 200915 Hydrogen Economy –Hydrogen an alternative fuel source to petroleum fuels For automobiles Electrical power generation –Pollution free fuel –Present dilemma – how to obtain sufficient amounts of H 2 –Splitting water using solar energy – one possible source for the needed H 2.
Copyright McGraw-Hill 200916 24.3 Carbon 0.09 % by mass of Earth’s crust An essential element of living matter A component of natural gas, petroleum and coal. Combines with oxygen to form carbon dioxide in the atmosphere Occur as carbonates in limestone and chalk. Found free in allotropic forms of diamond and graphite
Copyright McGraw-Hill 200917 Phase Diagram for Allotropic Forms of Carbon
Copyright McGraw-Hill 200918 catenation – carbon has the unique ability to form long chains stable rings –Responsible for the millions of carbon- containing compounds Reacts with –Metals to form carbides (strong bases), CaC 2 –Silicon to form carborundum, SiC –Nitrogen to form cyanides, Toxic Readily complexes metals
Copyright McGraw-Hill 200919 Cyanide Pond for Extracting Gold
Copyright McGraw-Hill 200920 Important oxides –Carbon monoxide (CO) Formed during incomplete combustion Colorless, odorless gas Used in metallurgical processes Used in organic synthesis Not acidic Only slightly soluble in water Burns to produce carbon dioxide
Copyright McGraw-Hill 200921 –Carbon dioxide (CO 2 ) Colorless and odorless gas Nontoxic—although it is a simple asphyxiant Acidic oxide – forms carbonic acid Uses –“ carbonated” beverages –Fire extinguishers –Manufacture of baking soda (NaHCO 3 ) –Manufacture of soda ash (Na 2 CO 3 ) –“Dry ice” as a refrigerant
Copyright McGraw-Hill 200922 24.4 Nitrogen and Phosphorous Nitrogen –Mineral sources of nitrogen: saltpeter (KNO 3 ) and Chile saltpeter (NaNO 3 ) –Nitrogen is an essential element of life A component of proteins and nucleic acids –N 2 is obtained by the fractional distillation of air –N 2 contains a triple bond and is stable –Forms variable oxidation states
Copyright McGraw-Hill 200924 Common (important) forms of nitrogen –Nitride ion, N 3−, a strong Br Ø nsted base –Ammonia, NH 3 Undergoes autoionization to produce the highly basic amide ion, NH 2 - –Hydrazine, N 2 H 4 Basic Reducing Agent
Copyright McGraw-Hill 200925 Important oxides –Nitrous oxide (N 2 O) Supports combustion Used as dental anesthetic –Nitric oxide (NO) Produced in atmosphere (form of nitrogen fixation) Colorless gas Produced in auto exhaust Paramagnetic Resonance stabilized
Copyright McGraw-Hill 200926 –Nitrogen Dioxide (NO 2 ) Toxic Paramagnetic Dimerizes to N 2 O 4 in the liquid and gas phases Acidic oxide –Shown in a disproportionation reaction with cold water
Copyright McGraw-Hill 200927 Nitric acid (HNO 3 ) –Powerful oxidizing agent –Can be reduced to NH 4 + –Aqua regia – 1:3 mixture of concentrated HCl and concentrated HNO 3 Even oxidizes gold –Oxidizes nonmetals to oxoacids –Used in manufacture of Fertilizers Drugs Explosives Dyes
Copyright McGraw-Hill 200928 Phosphorus –Occurs most commonly in nature as phosphate rocks calcium phosphate [Ca 3 (PO 4 ) 2 ] fluoroapatite [Ca 5 (PO 4 ) 3 F] –Elemental phosphorus produced by –Allotropic forms of phosphorus Red phosphorus White phosphorus Ca 5 (PO 4 ) 3 F
Copyright McGraw-Hill 200929 Allotropes of Phosphorus
Copyright McGraw-Hill 200930 –Reactions of phosphorus Formation of phosphine (PH 3 ) Formation of phosphoric acid Reaction with the halogens
Copyright McGraw-Hill 200931 Acid production from halides Reaction with oxygen to produce acidic oxides
Copyright McGraw-Hill 200932 Structure of P 4 O 6 and P 4 O 10
Copyright McGraw-Hill 200933 Oxoacids of phosphorus
Copyright McGraw-Hill 200934 24.5 Oxygen and Sulfur Oxygen –Most abundant element in Earth’s crust (46% by mass) –Atmosphere contains about 21% by volume (23% by mass) –Diatomic molecule (O 2 ) in the free state –Essential for human life –Alloptropic forms: O 2 and O 3 (ozone) –Strong oxidizing and bleaching agent
Copyright McGraw-Hill 200935 –Oxides Types of oxides –Normal oxide, O 2 2− –Peroxide, O 2 2− –Superoxide, O 2 − All are strong Br Ø nsted bases
Copyright McGraw-Hill 200936 Bonding in oxides – ionic to covalent left to right on the periodic table Acid-base character of oxides – –Basicity increases down a group –Peroxides H 2 O 2 (hydrogen peroxide) – most common example Basic Amphoteric Acidic
Copyright McGraw-Hill 200937 Structure of H 2 O 2
Copyright McGraw-Hill 200938 Polar Miscible with water Decomposes spontaneously Used as mild antiseptic (3% solution) or bleach agent (higher concentrations) Used as rocket fuel due to high heat of decompostion Serves as an oxidzing agent Serves as a reducing agent
Copyright McGraw-Hill 200939 –Ozone Toxic, light-blue gas Pungent odor Essential component of the atmosphere Structure Powerful oxidizing agent Preparation
Copyright McGraw-Hill 200940 Preparation of O 3
Copyright McGraw-Hill 200941 Sulfur –Constitutes about 0.06 % of Earth’s crust by mass –Occurs commonly in nature in the elemental form Sedimentary deposits Gypsum (CaSO 4. 2H 2 O) and various sulfide minerals such as pyrite (FeS 2 ) –Most common allotropic forms Monoclinic Rhombic – most stable form – S 8 FeS 2
Copyright McGraw-Hill 200942 Puckered Ring of S 8
Copyright McGraw-Hill 200943 –Extracted by the Fasch process
Copyright McGraw-Hill 200944 –Forms wide variety of oxidation numbers
Copyright McGraw-Hill 200945 –Hydrogen sulfide – H 2 S Used in qualitative analysis Preparation Colorless gas with odor of rotten eggs Toxic Weak diprotic acid Reducing agent in basic solution
Copyright McGraw-Hill 200946 –Oxides of sulfur Sulfur dioxide (SO 2 ) –Pungent colorless gas –Toxic –Preparation –Acidic oxide –Oxidation
Copyright McGraw-Hill 200947 Sulfur trioxide (SO 3 ) –Involved in acid rain –Used in the production of sulfuric acid (H 2 SO 4 ) in the contact process* *Vanadium(V) oxide (V 2 O 5 ) is the catalyst used for the key second step.
Copyright McGraw-Hill 200948 Sulfuric acid –Diprotic acid –Colorless, viscous liquid (m.p. 10.4°C) –Concentrated sulfuric acid is 98 % H 2 SO 4 by mass (density 1.84 g/cm3), 18 M. –Oxidizing strength of sulfuric acid depends on temperature and concentration. –Cold dilute sulfuric acid reacts with active metals
Copyright McGraw-Hill 200949 –Hot concetrated sulfuric acid reacts with less active metals –Depending on the reducing agent, sulfate may be reduced –Oxidizes nonmetals
Copyright McGraw-Hill 200950 Carbon disulfide (CS 2 ) –Colorless, flammable liquid (b.p. 46°C) –Preparation –SIightly soluble in water –Solvent for nonpolar substances Sulfur hexafluoride (SF 6 ) –Preparation –Colorless, nontoxic, inert gas
Copyright McGraw-Hill 200951 24.6 The Halogens The halogens—fluorine, chlorine, bromine, and iodine—are reactive nonmetals.
Copyright McGraw-Hill 200952 All are highly reactive and toxic Magnitude of reactivity and toxicity generally decreases from fluorine to iodine. The chemistry of fluorine differs from that of the rest of the halogens in the following ways: –Fluorine is the most reactive due to the relative weakness of the F−F bond. –The difference in reactivity between fluorine and chlorine is greater than that between chlorine and bromine.
Copyright McGraw-Hill 200953 –Hydrogen fluoride (HF) has a relatively high boiling point (19.5°C) –Hydrofluoric acid is a weak acid, all other hydrohalic acids are strong acids. –Fluorine uniquely reacts with cold sodium hydroxide solution to produce oxygen difluoride as follows: –Silver fluoride (AgF) is soluble. All other silver halides (AgCl, AgBr, and AgI) are insoluble.
Copyright McGraw-Hill 200954 Elemental state, halogens form diatomic molecules (X 2 ). In nature, always found combined with other elements. –Chlorine, bromine, and iodine occur as halides in seawater –Fluorine occurs in the minerals fluorite (CaF 2 ) and cryolite (Na 3 AlF 6 ). All isotopes of astatine (As) are radioactive
Copyright McGraw-Hill 200955 Preparation and Properties of F 2 and Cl 2 – determined by their strong oxidizing capability –Fluorine From liquid HF At 70 o C
Copyright McGraw-Hill 200956 Electrolytic Preparation of F 2
Copyright McGraw-Hill 200957 –Chlorine Electrolysis of molten NaCl Overall reaction Chlor-alkali process –Designed to prevent side reactions –Mercury cell –Diaphragm cell
Copyright McGraw-Hill 200958 Mercury Cell in the Chlor-alkali Process
Copyright McGraw-Hill 200959 Diaphragm Cell in the Chlor-alkali Process
Copyright McGraw-Hill 200960 Compounds of the Halogens –Either ionic or covalent. The fluorides and chlorides especially those belonging to the alkali metal and alkaline earth metal are ionic compounds (except halides of Be). Most of the halides of nonmetals are covalent compounds. –Oxidation numbers range from −1 to +7 except F which can only be 0 (in F 2 ) and −1, in all compounds.
Copyright McGraw-Hill 200961 –Hydrogen Halides Preparation from elements – can occur violently Preparation varies with the halogen, for example HCl HBr HF
Copyright McGraw-Hill 200962 –Industrial uses of hydrogen fluoride (HF) Reactive enough to etch glass Used in the manufacture of Freons –Industrial uses of hydrogen chloride (HCl) Preparation of hydrochloric acid Inorganic chlorides Various metallurgical processes
Copyright McGraw-Hill 200963 –Aqueous solutions of HX Acidic Variation in acid strength –Oxoacids – halogens form a series of acids Only Cl forms the entire series increasing acid strength
Copyright McGraw-Hill 200973 Carbon disulfide Sulfur hexafluoride The Halogens –Properties Special properties of fluorine –Preparation and Properites Preparation of fluorine Preparation of chlorine – chlor-alkali process –Mercury Cell –Diaphragm cell
Copyright McGraw-Hill 200974 Hydrogen Halides Oxoacids –Uses of the halogens Fluorine Chlorine Bromine Iodine