Chemical Principles II
Chemical Principles II CHEM 112
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This 0 page Class Notes was uploaded by Herta Weber on Sunday November 1, 2015. The Class Notes belongs to CHEM 112 at Pennsylvania State University taught by Staff in Fall. Since its upload, it has received 14 views. For similar materials see /class/233157/chem-112-pennsylvania-state-university in Chemistry at Pennsylvania State University.
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Date Created: 11/01/15
Chemistry 112002 Solids24 Structure and bonding in solids 1178 124 229 10 Dr Raymond Schaak Penn State University SPRING 2009 OUTLINE Inter vs intramolecular forces solids vs liquids vs gases 0 Crystalline vs amorphous solids Silicates glass and aluminosilicates Cement ceramics and composites 0 Classes of solids 0 Molecular solids 0 Network covalent solids Ionic solids 0 Metallic solids Allotropes of carbon 0 Bonding in the elements 0 Example problems Intra vs Intermolecular forces 321 Hymngm gas H Oxygen ma 0 molecular forces Hold together atoms in a molecule or compound molecular forces Hold together molecules in a gas liquid or solid Breaking bonds interactions energy Forming bonds interactions energy Solids vs liquids vs gases The importance of intermolecular forces a 5 Q quot Coolor C l compress oo gggq Heat or Heal 39 reduce 391 pressure Gas Liquid Crystalline solid Solid l mwmc Tcmpumlurn The chemistry of solids How are atoms arranged in solids Structure How are the atoms held together in solids Bonding How do classes of solids differ because of their bonding Atomic Molecular Covalent network Ionic Metallic Examples of materials with properties that are a direct result of their structure and bonding characteristics Crystalline vs amorphous solids Not all solids are crystalline Regular 3D array of atoms or molecules ice sugar NaCI No regular organization at a molecular level glass coal Copyrlgm2mS Pearson Prentice Hall Inc Silicates Silicates Si found in nature in combination with oxygen 2 Two vertices linked S39O 2 S39 o 4 Four types of structures 39 3 or 392 6 Example Absestos 1 orthosilicate MgsSi205OH4 fibrous i0 304439 units found silicate mineral crystal as isolated tetrahedron in shape mimics crystal Very few Silicate minerals structure and enstatite MgSi03 found in igneous Example ercon zrs3904 and metamorphic rocks not to be confused with cubic zirconia which is ZrO2 Repeating Junit Positive ions balance the charge hold chains or sheets together 4 Single strand silicate Chain SiZO Silicates Two vertices linked Si205X2 Example Talc M93Si2052OH2 Properties match Compare formula to crystal structure asbestos mineral Twnvdlim hsmnai gixmw shunt Sig f V IT IIFIIA IEgill llgi I39Igll llkll liFll 39squot Il iailquotI II iIZII ll 4VIjlquotiiiIf I zli 39 1icgus n gic avc gummyr Silicates Clays mica etc are 2D layered silicates Montmorillonite clay Naycao33AlyMg2Si4O1oOH239nH20 v 39 V quot v 39 17 53 17 Ailn LA A Mica Muscovite KA2AISi3O10FOH2 SiHcates 4 All four vertices linked SiO2 Example Quartz crystalline glass amorphous Properties of glass Transparent in visible and ultraviolet High refractive index Low thermal conductivity Low coefficient of thermal expansion But T9 1600 C fused silica Slasss Using chemistry to modify the properties of glass Lower processing temperature Add oxides such as NaZO CaO 8203 etc VVhy Example Sodalime glass windows contains NaZO and CaO and softens at 600 C How is glass made Why does the processing temperature matter Glass Other kinds of glass Sodalime glass C00 deep blue cobalt glass Use K20 instead of Map harder glass higher melting point Use PbO instead of CaO denser leaded glass greater refractive index bends light differently WHY Add BZO3 with SiO2 and Na20 borosilicate glass low thermal expansion coefficient so doesn t crack when heated or cooled Add AgCl or AgBr photochromic glass dark when exposed to light clear with little or no light Aluminosilicates Replace some of the Si4 in silicates with Ali Why Example of common aluminosilicates Zeolites porous cagelike structures naturally occurring and molecular seives and catalysts variety of pore sizes amp uses Cement is a glass Cement is a homogeneous mixture of amorphous and crystalline phases makes a tougher material H20 CaBSiO5 a Ca38i2073H20 CaOH2 CaZSiO4 glassy ca 70 of cement crystalline crystalline silicate powders Ceramic Composites Composite Two or more materials making up a ceramic Result Tougher ceramic Most effective method Add fibers to ceramic material Example SiC bers added to aluminosilicate glass Fiber must have a length 2100 times its diameter Carbon nanotubes are added to polymer resins create high strength materials Ceramics Inorganic typically nonmetallic solids Crystalline Oxides Al203 Zr02BeO Carbides SiC Ca2C Nitrides BN Silicates SiO2 mixed with metal oxides Aluminosilicates Al203 SiO2 metal oxides Mica Talc Pottery Clay Amorphous glasses Properties of ceramics 0 Typically hard and brittle Less dense than metals lighter More elastic than metals Resist corrosion and wear don t deform 0 Stable at high temperatures High melting 0 Can be covalent network andor ionic Usually electrical insulators Classes of solids Atomic Solids noble gases Molecular Solids Van der Walls forces hydrogen bonds discrete molecules includes polymers Covalent Network Solids lattice of covalent bonds Ionic Solids salts ionic bonds Metals metallic bonds also alloys Bonding in molecular solids Examples of MolecularAtomic solids Ar atomic solid water ice CO2 dry ice hydrocarbons gasoline alcohols av methane b J Bonding in network covalent solids Allotropes of carbon Atoms held together in large networks Allotrope chains planes and 3D by Structure Uses Diamond 4 5 bonds to each C hardest substance known sp3 hybridization abrasive tetrahedral drill bits cutting tools Gem Graphite 3 5 bonds to each C conducts current soft sp2 hybridization batteries as electrode Planar pencils delocalized n bonds lubricant van derwaals forces between planes Fullerenes 3 5 bonds to each C In development sp2 hybridization as well as nanotubes delocalized n bonds eg C60 looks like a soccer ball Carbon amorphous Black tires ink pigments carbon paper Allotropes of carbon This is what the different allotropes of carbon look like 0 P Diamond Graphite Carbon nanotube fullerene with one side extended into a tube variable Fullerene C60 lengths Bonding in ionic solids Atoms ions held together by bonds Examples of Ionic Solids NaBr CaCO3 NH4C FeCl2 Structures of ionic solids Bonding in metallic solids Note that multiple types of bonding can be Atoms metals held together by bonds present in the same compound Q Barium Oxygen 9 Titanium wmmczwsvemmmwau Inc What properties of metals does this help to explain Boiling points of metallic solids vary a lot why Structures of metallic solids Most metals adopt one of a few simple structures 90 90 go 90 0900 K J r 0 o G o Q Primitive cubic Bodycentered cubic Cowman c 2006 Pearson mm Hall m Facecentered cubic l Alum mm ml at innitr linlnm at s DMI IS l s mrlwrs f mam al 0 law gnlnm 3 5mmch FainEntered liudyrrunlt39md WK mm V l rmlllncctlbzc Crystal lattice 3D array of atoms Unit cell Repeating unit of crystal lattice Examples face centered cubic fcc body centered cubic bcc Summary of bonding in solids Crystal Type Unit Forces Example Properties atomic atoms dispersion Ar Kr v low MP polar or dispersion sugar molecular oquotPolar dipoledipole CHM C02 soft low MP molecules n lng H20 atoms in covalent diamond covalent covalent graphite high MP hard network quartz cations and ionic anions electrostatic NaCl high MP brittle metals wide range of metallic atoms metallic Cu Fe MP softer bonds Al Ni malleable Bonding in the elements What types of bonds would you expect for Metals Metalloids semimetals Nonmetals noble gases Nonmetals diatomic gases Nonmetals S P Se Nonmetals C Bonding in the elements MAIN GROLlPS MAIN GROLlPS 1A 7A 8A 2A 3A 4A 5A 6A Atomic Molecular Network covalent Metallic 1 Example problems Which type of crystal will form when CGH6 benzene solidi es 1 ionic 2 molecular 3 metallic 4 covalentnetwork 5 amorphous Indicate the type of crystal molecular metallic covalentnetwork or ionic each of the following would form upon solidi cation 1 Zr 2 N204 3 SiO2 4 Ne 5 NiClO32 For each of the following pairs of substances predict which will have the higher melting point KBr Br2 SiO2 CO2 Ar Xe
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