Chapter 22 Chemistry of the Nonmetals 2011, NKMB Co., Ltd. Chemistry, Julia Burdge, 2 st Ed. McGraw Hill. Mr. Truong Minh Chien ; losedtales@yahoo.com http://tailieu.vn/losedtales http://mba-programming.blogspot.com 2 Nanotubes • nanotubes – long, thin, hollow cylinders of atoms • carbon nanotube = sp 2 C in fused hexagonal rings  electrical conductors • boron-nitride nanotubes = rings of alternating B and N atoms  isoelectronic with C  similar size to C  average electronegativity of B & N about the same as C  electrical insulators Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 3 Insulated Nanowire Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 4 Properties of BN and C Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 5 Main Group Nonmetals Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 6 Atomic Radius and Bonding • atomic radius decreases across the period • electronegativity, ionization energy increase across the period • nonmetals on right of p block form anions in ionic compounds  often reduced in chemical reactions  making them oxidizing agents • nonmetals on left of p block can form cations and electron-deficient species in covalent bonding • nonmetals near the center of the p block tend to use covalent bonding to complete their octets • bonding tendency changes across the period for nonmetals from cation and covalent; to just covalent; to anion and covalent Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 7 Silicates • the most abundant elements of the Earth’s crust are O and Si • silicates are covalent atomic solids of Si and O  and minor amounts of other elements  found in rocks, soils, and clays  silicates have variable structures – leading to the variety of properties found in rocks, clays, and soils Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 8 Bonding in Silicates • each Si forms a single covalent bond to 4 O  sp 3 hybridization  tetrahedral shape  Si-O bond length is too long to form Si=O • to complete its octet, each O forms a single covalent bond to another Si • the result is a covalent network solid Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 9 Quartz • a 3-dimensional covalent network of SiO 4 tetrahedrons • generally called silica • formula unit is SiO 2 • when heated above 1500°C and cooled quickly, get amorphous silica which we call glass Chemistry, Julia Burdge, 2 nd e., McGraw Hill. 10 Aluminosilicates • Al substitutes for Si in some of the lattice sites • SiO 2 becomes AlO 2 − • the negative charge is countered by the inclusion of a cation  Albite = ¼ of Si replaced by Al; Na(AlO 2 )(SiO 2 ) 3  Anorthite = ½ of Si replaced by Al; Ca(AlO 2 ) 2 (SiO 2 ) 2 Chemistry, Julia Burdge, 2 nd e., McGraw Hill. [...]... Forms of Carbon • coal is a mixture of hydrocarbons and carbon-rich particles  the product of carbonation of ancient plant material  carbonation removes H and O from organic compounds in the form of volatile hydrocarbons and water • anthracite coal has highest C content • bituminous coal has high C, but high S • heating coal in the absence of air forms coke  carbon and ash • heating wood in the absence... shared O, the structure is called a pyroxene formula unit SiO32- • • chains held together by ionic bonding to metal cations between the chains  diopside = CaMg(SiO3)2 where Ca and Mg occupy lattice points between the chains Chemistry, Julia Burdge, 2nd e., McGraw Hill 12 Double Chain Silicates • some silicates have 2 chains bonded together at ½ the tetrahedra – these are called amphiboles • often results... BnHn+6 consisting of cage B missing two or three corners Tro, Chemistry: A Molecular Approach 21 Carbon • exhibits the most versatile bonding of all the elements • diamond structure consists of tetrahedral sp3 carbons in a 3-dimensional array • graphite structures consist of trigonal planar sp2 carbons in a 2-dimensional array sheets attracted by weak dispersion forces • fullerenes consist of 5 and 6 member... coke  carbon and ash • heating wood in the absence of air forms charcoal  activated carbon is charcoal used to adsorb other molecules • soot is composed of hydrocarbons from incomplete combustion  carbon black is finely divided form of carbon that is a component of soot  used as rubber strengthener Tro, Chemistry: A Molecular Approach 26 Allotropes of Carbon Buckminsterfullerene Sublimes between 800°C... Made of Individual Units • O of SiO4 picks up electrons from metal to form SiO44− • if the SiO44− are individual units neutralized by cations, it forms an orthosilicate  willemite = Zn2SiO4 • when two SiO4 units share an O, they form structures called pyrosilicates with the anion formula Si2O76−  hardystonite =Ca2ZnSi2O7 Chemistry, Julia Burdge, 2nd e., McGraw Hill 11 Single Chain Silicates • if the. .. Nanotubes Tro, Chemistry: A Molecular Approach 29 Nanocars Tro, Chemistry: A Molecular Approach 30 Carbides • carbides are binary compounds of C with a less electronegative • element ionic carbides are compounds of metals with C  generally alkali or alkali earth metals  often dicarbide ion, C22− (aka acetylide ion)  react with water to form acetylene, C 2H2 • covalent carbides are compounds of C with... C sits in holes in the metal lattice  hardens and strengthens the metal without affecting electrical conductivity  steel and tungsten carbide Tro, Chemistry: A Molecular Approach 31 Calcium Carbide Tro, Chemistry: A Molecular Approach 32 Cementite Fe3C regions found in steel Tro, Chemistry: A Molecular Approach 33 Carbon Oxides • CO2  0.04% in atmosphere  increased by 25% over the past century ... to form glasses of different compositions Tro, Chemistry: A Molecular Approach 19 Boranes closo-Boranes • compounds of B and H • used as reagent in hydrogenation of C=C • closo-Boranes have formula BnHn2− and form closed polyhedra with a BH unit at each vertex Tro, Chemistry: A Molecular Approach 20 Boranes nido-Boranes and arachno-Boranes • nido-Boranes have formula BnHn+4 consisting of cage B missing... = Ca2(OH)2Mg5(Si4O11)2 Chemistry, Julia Burdge, 2nd e., McGraw Hill 13 Sheet Silicates • when 3 O of each tetrahedron are shared, the result is a sheet structure called a phyllosilicate • formula unit = Si2O52− • sheets are ionically bonded to metal cations that lie between the sheets • talc and mica Chemistry, Julia Burdge, 2nd e., McGraw Hill 14 Mica: a Phyllosilicate Tro, Chemistry: A Molecular... aliphatic than aromatic Tro, Chemistry: A Molecular Approach 27 Nanotubes • long hollow tubes constructed of fused C6 rings • electrical conductors • can incorporate metals and other small molecules and elements used to stabilize unstable molecules • single-walled nanotubes (SWNT) have one layer of fused rings • multi-walled nanotubes (MWNT) have concentric layers of fused rings Tro, Chemistry: A Molecular . Chapter 22 Chemistry of the Nonmetals 2011, NKMB Co., Ltd. Chemistry, Julia Burdge, 2 st Ed. McGraw Hill making them oxidizing agents • nonmetals on left of p block can form cations and electron-deficient species in covalent bonding • nonmetals near the center of