无机化学英文课件：07 group IVA

1、Group IV A or 14,Carbon, Silicon, Germanium, Tin, Lead,Carbon,Graphite,Diamond,Fullerene,Bucky Tube,Graphite - diamond,100 kbar, 12002800 K,Cr, Fe or Ni,Graphite,Soft and black and the stable,common,form of carbon. Very light and resistant More 2D like; sp2 Orbitals. Atom is at the corners of fused

2、hexagon in parallel layers Strong bonds within layers and weak bond between layers Good conductor of electricity,Diamond,Abrasive Gem,Diamond,Hard and transparent and the unusual form of carbon. Strong thermal conductivity More 3D like behavior; sp3 orbital. Atom is bound to four other carbon atoms

3、in a regular repetitive pattern. Strong covalent bonding in 3 dimensions Bad electrical conductor,Diamonds are not forever!) It will turn into graphite (given time). (Faster if you heat it up or bombard it with high energy ions.,Fullerenes C60,Discovered in 1985 by Harry Kroto University of Sussex,

4、England Richard Smalley and Robert Curl Jr Rice University, Texas 1996 Nobel Prize in Chemistry,H.Kroto R. Smalley R. Curl,Smalleys apparatus for generating and detecting buckyball,Schematic of a mass spectrometer,.in the field of Observation, chance only favors the prepared mind” Louis Pasteur,C60,

5、Bucky Ball; fullerene,J.R. Heath, S.C. OBrien, H.W. Kroto, R.F. Curl, R.E. Smalley, Nature 318 , 162, (1985,Fullerene,C60 - A third allotropic form of very stable spheres(1985) - Formed when graphite is evaporated in an inert atmosphere. - Assumed C60 consists of 12 pentagons and 20 hexagons with ca

6、rbon atoms at each corner, as a soccer ball. - Names New carbon ball C60 Buckminsterfullerene ( R.Buckminster Fuller : The geodesic dome 1967 ) Buckyball,All have 12 pentagonal faces, 145.5 pm on a side. C60 has 20 hexagonal faces, 139 pmT= 5K on a side. The C=C between two pentagons is electron ric

7、h, The pentagons themselves are electron poor. The LUMO of C60 is triply degenerate. Fullerides C60-1 to 6, C603- are superconducting below T = 28K. Fullerenes may encapsulate metal atoms or small clusters. Clusters lose 3 electrons to the fullerene. La C60 is La3+ C603,The Fullerenes Molecular form

8、s of Carbon,What is happening in current research with Buckyball,Model of C60 docked in the binding site of HIV-1 protease,Fullerene Pyrrolidine and Osmium Tetroxide derivatives of C60,C50-containing soot ( 90 g) was synthesized in a modified graphite arc-discharge process in which 0.013 atm of CCl4

9、 was added to 0.395 atm of helium. The products in the toluene extract from the soot were isolated with multistage high-performance liquid chromatography . and 2 mg of C50Cl10 with 99.5% purity was obtained,The C50Cl10 thus obtained is moderately soluble in some organic solvents, e.g., carbon disulf

10、ide, toluene, and benzene, as a lemon yellowcolored solution,Science, Vol 304, Issue 5671, 699 , 30 April 2004,Rational Side of Materials Chemistry: Rational Doping: C60 insulator Semiconductor Superconductor La2CuO4 Magnetic insulator Bad Metal Superconductor,K,K3C60,Nanotubes C1,000,000 and beyond

11、,Discoverer: Sumio Iijima Carbon Nanotubes (CNT) 1991 multiwalled CNT coaxial cylinders with a hollow core 1993 single-walled CNT Roll up sheets of hexagons,Nanotubes C1,000,000 and beyond,Diameter 1-30 nm Length microns Interlayer Spacing 0.347 nm Graphite interlayer spacing 0.337 nm,IBM,Do C60 and

12、 CNT really exist,NUS Surface Science Laboratory,Seeing is believing,Yacobson and Smalley,Richard Smalley Image Gallery,Arc Discharge,Catalytic Decomposition,H, CH4 or CO,Temperature Programmable Furnace,Quartz Tube,Catalyst,CO/ CH4,CNT,Co/La2O3,600-750 oC,2CO,C + CO2,CH4,C + 2H2,2-dimensional hexag

13、onal lattice of carbon sp2 hybridized carbon atoms Basis for C-60 (bucky balls), nanotubes, and graphite Among strongest bonds in nature,What is graphene,A. K. Geim 碳酰亚氨钙；氰氨基钙 cyanamide - can be trimerized to melamine,Interstitial Carbide,Where the carbon-metal electronegativity difference is smalle

14、r, as in transition metal carbides, MxCy compounds are called interstitial carbides. eg., WC. Bonding is more covalent, properties are metallic,Compounds of Carbon,Structure： CO(6+8=14e-) and N2（27=14e-） Isoelectronic, similar structure,One bond Two bond,Oxides Monooxide (CO,Properties of CO： as lig

15、and，forming carbonyl complexes Fe(CO)5, Ni(CO)4, Co2(CO)8 C as coordinating atom。 Reductant,Highly toxic,Dioxide (CO2,structure：O=C=O,O,C=O bond length 124pm as in CH3-C-CH3,C-O bond length in CO2: 116pm,C：sp,Solid state: Dry ice,Carbonates,CO2 soluble in H2O，mostly as CO2H2O， A few as H2CO3,Structu

16、re of CO32,CO32-(6+38+2=32e-) and BF3(5+39=32e-) are isoelectronic,C：sp2,Thermal stability of carbonate,H2CO3MHCO3M2CO3,Thermal stability increases down a group BeCO3 MgCO3 CaCO3 SrCO3 BaCO3 Dec T/ 100 540 900 1290 1360,Low thermal stability for transition metal carbonate CaCO3 PbCO3 ZnCO3 FeCO3 Dec

17、 T / 900 315 350 282 VE config. 8e_ (18+2)e_ 18e_ (9-17)e_,Why,r(M2+) more polarizing ，MCO3 less stable； M2+ with 18e_，(18+2)e_ ，(9-17)e_ electronic config. Higher polarzing power comparing with 8e_， reducing MCO3 stability,Easily Polarizable,Solubility of carbonate,soluble：Na2CO3 NaHCO3 K2CO3 KHCO3

18、 100solubility 45 16 156 60 (g/100g H2O,other carbonates (including Li) insoluble in H2O，bicarbonates more soluble than carbonates,H-bond,dimer or polymer form,Hydrolysis of carbonates in H2O,OH,HCO,O,H,CO,3,2,2,3,metal ions with hydroxides as strong base form carbonates。 eg：Ba2+、Sr2+、Ca2+ and Ag+ e

19、tc,Type of carbonate precipitates,metal ions with hydroxides as medium base form basic carbonates。 eg：Pb2+、Bi3+、Cu2+、Cd2+、Zn2+、Hg2+、Co2+、Ni2+ and Mg2+ etc,metal ions that are easily hydrolysable or amphoteric form hydroxide precipitates. eg：Al3+、Fe3+、Cr3+、Sn2+、Sn4+ and Sb3+etc,Intercalation compound

20、s of graphite,Silicon,IBM Copper interconnects,Semiconductors,Germanium and Silicon form a diamond lattice. Bonding electrons in Si and Ge are held less tightly than in C,Compounds in which the electrical conductivity increases with increased temperature, light, or addition of impurities are semicon

21、ductors,VB,CB,eg,eg,e- e- e- e- e,h+ h+ h+ h+ h,Low T,High T,n-type (Si + P) p-type (Si + B) diodes pn junction transistor pnp or npn,CONVENTIONAL LIGHT-EMITTING DIODES,Atomic Semiconductor Devices (The Zerner Diode,Limitations,Typical LED Materials,640-670nm Red GaAlAsP $0.40 525nm Green GaN $2.95

22、Blue SiC $1.29 and 430nm GaN $1.00 400-418nm Violet GaN $0.80,Tunability Patterning Quantum Confinement High Cost of Fabrication,Cadillac DeVille LED taillights can illuminate up to 0.2 s faster than cold incandescent taillamps,Tin,Known since 3000B.C,Tin is one of the elements which has an alchemic

23、al symbol,Tin is commonly available as the mineral cassiterite, SnO2. Reduction with burning coal results in tin metal. This was probably how tin was made by the ancients,SnO2 + 2C Sn + 2CO,Isotopes of Tin,Sn -Sn,13.2oC,white” tin Metallic in appearance. Tetragonal structure. Highly crystalline,grey

24、” tin Crumbly (brittle) Cubic structure,Prolonged cooling causes conversion to alpha form,Lead,Pb organ Oxford, England,Uses,Yellow and Red Pigments,Trends in Group 14 Bond Energies The decrease in bond strength as one goes down the group is marked and modified only by p-d bonding. d bonding diminis

25、hes: Si Ge Sn Pb C. There are no germanium analogues to the silicones. The exceptional stability of the Si-O bond is not duplicated in the Ge-O bond. Stability of the M(II) state: Pb Sn Ge Si C. Ability to catenate: C Si Ge Sn Pb. For the alkane analogues: SinH2n+2 n = 8; GenH2n+2 n = 5. Hydrides of

26、 germanium are not pyrophoric and are unaffected by acid/base, unlike the silanes. Hydrides of tin and lead are of marginal stability,Properties,Reaction with Base,Reaction with HF,2.Silicic acid and silicates,Properties,12,2,10,1,3,2,10,6,1,10,7,1,SiO,H,low solubility，biacid,K,K,Preparation,Silica

27、gel containing small amount of CoCl2will change color at different H2O contents,Silicic acid as gel,Silica gel,H2O,soluble：Na2SiO3 、K2SiO3 insoluble: with characteristic color,silicates,Si sp3,Tetrahedral arrangement of Si-O,silica,Structure of silica,halides SiX4,SiF4 SiCl4 SiBr4 SiI4 State g l l s,hydrolysis,Hydride (silane SinH2n+2,property,simplest：SiH4,pyrophoricity,hydrolysis,strong reductant,low thermal s