碳族元素Chapter14Thecarbonfamilyelements14章碳族元素碳族元素.ppt

第十四章 碳族元素 Chapter 14 The carbon family elements,Carbon (C) Silicon (Si) Germanium (Ge) Stannum (Sn) Plumbum (Pb),Tin,Lead,14-1Carbon and its compounds 一、General properties 1. 根據(jù)鍵的數(shù)目,碳可采取sp2、sp3雜化,其最大配 位數(shù)為4 2. 由于碳碳單鍵的鍵能特別大,所以CC鍵非常穩(wěn)定 ,具有形成均鏈的傾向 從碳到氮的單鍵鍵能的突減，是由于氮原子非鍵電 子對排斥的緣故。,二、Simple substance 1. 在第二周期中，氟、氧、和氮都以雙原子分子存在 F2、O2和N2；而碳存在多聚物，其理由為: O2和N2 的多重鍵要比單鍵(均鍵)強(qiáng)得多 2. Allotropes: diamond graphite fullerene carbin (carbon fibers) (1) 熵 Scarbin Sgraphite Sdiamond (2) dc-c (nm): diamond graphite carbin,E (kJmol1) 494 210 + 210, 946 250 +250+250,E (kJmol1) 627 374 + 374,(3) Cgraphite Cdiamond H 0 S 0 根據(jù)平衡,需要高壓6e91e10Pa，(because of the insignificant reduction of volume)，升高溫度 不利于平衡的移動(dòng),但為了達(dá)到該過程可以接受的速率 ,反應(yīng)溫度大約在2000，近來已發(fā)明一種低壓生產(chǎn) 金剛石的方法:把金剛石晶種(seed)放在氣態(tài)碳?xì)浠?物( 甲烷methane, ethane )中,溫度升高到1000,可 以得到金剛石粉末或者crystal whiskers CVD technique for diamond growth,The fundamental problem of diamond synthesis is the allotropic nature of carbon. Under ordinary conditions graphite, not diamond, is the thermodynamically stable crystalline phase of carbon. Hence, the main requirement of diamond CVD is to deposit carbon and simultaneously suppress the formation of graphitic sp2-bonds. This can be realized by establishing high concentrations of non-diamond carbon etchants such as atomic hydrogen. Usually, those conditions are achieved by admixing large amounts of hydrogen to the process gas and by activating the gas either thermally or by a plasma.,Due to its combination of unique physical properties diamond is an outstanding material. Besides its unrivaled hardness diamond exhibits ultrabroadband transparancy ranging from deep UV to the microwave regime, and a thermal conductivity at room temperature which is higher than that of any other material. The excellent mechanical, thermal, optical and insulating properties of diamond became accessible through the advent of low pressure Chemical Vapour Deposition (CVD) techniques which allow diamond in the form of extended films and free-standing wafers to be fabricated.,(4) C60 由12個(gè)五邊形和20個(gè)六邊形組成,每個(gè)該原子以sp2 雜化軌道與相鄰的三個(gè)碳原子相連，剩余的p軌道在 C60球殼的外圍和內(nèi)腔形成球面鍵,從而具有芳香性 歐拉方程：面數(shù)(F) + 頂點(diǎn)數(shù)(V) = 棱數(shù)(E) + 2 a. structure:根據(jù)歐拉定理，通過12個(gè)五邊形和數(shù) 個(gè)六邊形的連接可以形成封閉的多面體結(jié)構(gòu) C60為第一個(gè)五邊形間互不相鄰的碳籠 不存在六邊形的最小碳籠為C20,32個(gè)面，60個(gè)頂點(diǎn)，90條棱 12個(gè)正五邊形和20個(gè)正六邊形 F + V = E + 2,Fullerene Discoverers Win Chemistry Nobel The Nobel Prize in chemistry was awarded today to two Americans and one British researcher for their discovery of fullerenes, a new class of all-carbon molecules shaped like hollow balls. The researchers, Richard E. Smalley and Robert F. Curl Jr. of Rice University in Houston, and Harold W. Kroto of the University of Sussex in Brighton, United Kingdom, made their discovery in 1985 in Smalleys lab at Rice while working together to study how carbon atoms cluster. “The award is richly deserved,“ says Robert Haddon, a fullerene chemist at Lucent Technologies Bell Labs in Murray Hill, New Jersey. “It led to a totally new field of chemistry.“ Today, fullerenes-which are popularly known as buckyballs-are being investigated for everything from new superconductors and three-dimensional polymers, to catalysts and optical materials, although they have yet to spawn any commercial applications. Before the groups discovery, crystalline carbon was thought to adopt only a handful of different molecular architectures, including those found in diamond and graphite. But the researchers discovered that sheets of carbon atoms arranged in a pattern of hexagons and pentagons can curl up and ultimately close to form hollow cages. And because the number of atoms in the cage can vary, an almost infinite number of fullerene shapes may exist.,Tetrahedron Cube Octahedron Dodecahedron Icosahedron,Triangles. The interior angle of an equilateral triangle is 60 degrees. Thus on a regular polyhedron, only 3, 4, or 5 triangles can meet a vertex. If there were more than 6 their angles would add up to at least 360 degrees which they cant. Consider the possibilities: 3 triangles meet at each vertex. This gives rise to a Tetrahedron. 4 triangles meet at each vertex. This gives rise to an Octahedron. 5 triangles meet at each vertex. This gives rise to an Icosahedron Squares. Since the interior angle of a square is 90 degrees, at most three squares can meet at a vertex. This is indeed possible and it gives rise to a hexahedron or cube. Pentagons. As in the case of cubes, the only possibility is that three pentagons meet at a vertex. This gives rise to a Dodecahedron. Hexagons or regular polygons with more than six sides cannot form the faces of a regular polyhedron since their interior angles are at least 120 degrees.,The Platonic Polydedra: f=2+e-v,b. properties: 科學(xué)家認(rèn)為C60將是21世紀(jì)的重要 材料 (i) C60分子具有球形的芳香性,可以合成C60F2 ，作 為超級潤滑劑 (ii) C60籠內(nèi)可以填入金屬原子而形成超原子分子, 作為新型催化劑或催化劑載體，具有超導(dǎo)性 (iii) C60晶體有金屬光澤，其微晶體粉末呈黃色， 易溶于苯，其苯溶液呈紫紅色。C60分子特別穩(wěn)定，進(jìn) 行化學(xué)反應(yīng)時(shí)，C60始終是一個(gè)整體,Types of carbon nanotubes: Single-walled,The (n,m) nanotube naming scheme can be thought of as a vector (Ch) in an infinite graphene sheet that describes how to “roll up“ the graphene sheet to make the nanotube. T denotes the tube axis, and a1 and a2 are the unit vectors of graphene in real space.,For a given (n,m) nanotube, if 2n + m=3q (where q is an integer), then the nanotube is metallic, otherwise the nanotube is a semiconductor. Thus all armchair (n=m) nanotubes are metallic, and nanotubes (5,0), (6,4), (9,1), etc. are semiconducting. In theory, metallic nanotubes can have an electrical current density more than 1,000 times greater than metals such as silver and copper.,三、Compounds 1. - 4 O.S. 水解性(或與水反應(yīng)) Al4C3 + 12H2O = 4Al(OH)3 + 3CH4 CaC2 + 2H2O = Ca(OH)2 + HCCH 2. + 4 O.S (1) CHal4 a. 制備 CS2 + 3Cl2 = CCl4 + S2Cl2 b. 性質(zhì) 水解性,CHal4 + 2H2O = CO2 + 4HHal 從熱力學(xué)上看是可行的，它們之所以不能水解是由 于在通常條件下缺乏動(dòng)力學(xué)因素，碳的配位數(shù)已飽 和，不能與水分子結(jié)合 從CF4 CI4隨著鍵長的增大,鍵的強(qiáng)度減弱,穩(wěn)定 性減弱,活潑性增強(qiáng),(2) COHal2（鹵氧化碳或碳酰鹵）: 所有的COHal2比CHal4的化學(xué)性質(zhì)活潑,特別是它 們易水解: COCl2 + H2O = CO2 + 2HCl 它們都有極性,都是平面三角形。 COCl2 (光氣) 是劇毒的 光氣的制備: CO + Cl2 =COCl2,(3) CS2 a. Preparation (i) C+ 2S = CS2 (900C) (ii) 4S + CH4 = CS2 + 2H2S (600C, Al2O3或硅膠) b. Properties CS2易揮發(fā),易燃的無色的有機(jī)溶劑 明顯水解 CS2 + 2H2O = CO2 + 2H2S 與堿性硫化物反應(yīng) Na2S + CS2 = Na2CS3,(4) CO32- CS32- CN22- a. structure b. 性質(zhì) (i) 碳酸鹽: 正鹽中除堿金屬(不包括Li+)，銨及Tl+鹽 外都難溶于水,許多金屬的酸式鹽的溶解度大于正鹽,但 SNaHCO3 SNa2CO3 解釋:這是由于在NaHCO3溶液中HCO3-以氫鍵相 連成二聚或多聚鏈狀離子,降低了它們的溶解度 熱穩(wěn)定性： H2CO3 MHCO3 M2CO3,(ii) 硫代碳酸鹽 K2S + CS2 = K2CS3 = H2CS3 H2CS3是高折射率油狀物，易分解成H2S和CS2 H2CS3的水溶液為弱酸，在水中緩慢分解 H2CS3 + 3H2O = H2CO3 + 3H2S (iii) 氨基腈化物 (Cyanamide) (CN22-)（氮代碳酸鹽） H2CN2 ( Hydrogen dinitride carbonate )是無色晶 體，易溶于水，alcohol和ether，顯示弱酸性，在有 機(jī)溶劑中可能存在互變異構(gòu)平衡,H+,H2CN2在水中緩慢分解: H2CN2 + 3H2O = H2CO3 + 2NH3 3. +2 O.S. HCOOH = CO + H2O (濃硫酸，加熱) CO結(jié)構(gòu)式： 使減小 CO + PdCl2 + H2O = Pd + CO2 + 2HCl Cu(NH3)2+可以吸收CO，所以CO比N2活潑,常溫,CO2 v.s. CO,14-2 Silicon and its compounds 一、General properties: 1. 由于Si的原子半徑大，電離能低，電子親合能和 極化率高，因此Si在化學(xué)性質(zhì)上與碳有許多不同之處，例如Si和Si之間基本上不形成pp鍵，換言之，Si的sp或sp2雜化不穩(wěn)定。 2. 由于Si原子的價(jià)軌道存在3d空軌道,所以Si的最大 配位數(shù)可以達(dá)到6，可以形成dp鍵，例如N(SiH3)3中N原子采取sp2雜化，分子為平面三角形。這是由于N原子上的孤對電子對占有Si原子的3d空軌道，形成dp鍵所致。顯然N(CH3)3與N(SiH3)3的堿性也不同，前者的Lewis堿性大于后者。 3. Si在自然界中占第二位，僅次于氧,二、The simple substance 1. Properties (1) 在通常情況下，硅非常惰性 ，但加熱時(shí)與許多非金屬單質(zhì) 化合，還能與某些金屬反應(yīng) 2Mg + Si = Mg2Si (2) 硅遇到氧化性的酸發(fā)生鈍化性,它可溶于HFHNO3的混合 酸中 3Si + 4HNO3 + 18HF = 3H2SiF6 + 4NO + 8H2O (3) 硅溶于堿并放出H2: Si + 2KOH + H2O = K2SiO3 + 2H2 (4) 硅在高溫下與水蒸氣反應(yīng): Si + 3H2O = H2SiO3 + 2H2,Silicon nitride (Si3N4) is a hard, solid substance, that can be obtained by direct reaction between silicon and nitrogen at high temperatures. Silicon nitride is the main component in silicon nitride ceramics, which have relatively good shock resistance compared to other ceramics. Rollers made of silicon nitride ceramic are sometimes used in high-end skateboard bearings, due to the materials shock and heat-resistant characteristics. It is also used as an ignition source for domestic gas appliances, hot surface ignition. In microelectronics, silicon nitride is usually formed using chemical vapor deposition (CVD) method, or one of its variants, such as plasma-enhanced chemical vapor deposition (PECVD). It is usually used either as an insulator layer to electrically isolate different structures or as an etch mask in bulk micromachining. As a passivation layer for microchips, it is superior to silicon dioxide, as it is a significantly better diffusion barrier against water molecules and sodium ions, two major sources of corrosion and instability in microelectronics. It is also used as a dielectric between polysilicon layers in capacitors in analog chips. Bulk, monolithic silicon nitride is used as a material for cutting tools, due to its hardness, thermal stability, and resistance to wear. It is especially recommended for high speed machining of cast iron. For machining of steel, it is usually coated by titanium nitride (usually by CVD) for increased chemical resistance.,Lightning Arresters,In telegraphy and telephony a lightning arrester is placed where wires enter a structure, preventing damage to electronic instruments within and ensuring the safety of individuals near them. Lightning arresters, also called surge protectors,are devices which are connected between each electrical conductor in a power and communications systems and the earth. These provide a short circuit to the ground that is interrupted by a non-conductor over which lightning jumps. Its purpose is to limit the rise in voltage when a communications or power line is struck by lightning. The non-conducting material may consist of a semi-conducting material like silicon carbide or zinc oxide, or a spark gap. Primitive varieties of such spark gaps are simply open to the air, but more modern varieties are filled with dry gas and provided with a small amount of radioactive material to encourage the gas to ionize when the voltage across the gap reaches a specified level. Other designs of lightning arresters use a glow-discharge tube (essentially like a neon glow lamp) connected between the protected conductor and ground, or any one of a myriad of voltage-activated solid-state switches called varistors or MOVs. Lightning arresters built for substation use are impressive devices, consisting of a porcelain tube several feet in length and several inches in diameter, filled with disks of zinc oxide. A safety port is supplied on the side of the device to vent the occasional internal explosion without shattering the porcelain cylinder.,2. preparation: (1) SiCl4 + 2Zn = Si + 2ZnCl2 (2) SiO2和C混合，在電爐中加熱: SiO2 + 2C = Si + 2CO (3) SiO2 + CaC2 = Si + Ca + 2CO (4) 硅烷的分解: SiH4 = Si + 2H2 用作半導(dǎo)體用的超純硅，需用區(qū)域熔融的方法提純,99.999999%,三、Compounds 1. 硅的金屬化合物與硅合金 (1) IA、 IIA族硅化物: Ca2Si , CaSi , CaSi2 不穩(wěn)定，與水反應(yīng) (2) 副族元素硅化物: Mo3Si , Mo5Si3 , MoSi , MoSi2 （2050） 高熔沸點(diǎn)，不溶于HF和王水，僅溶于HF HNO3混合液或者在堿液中 WSi2（2165），Ti5Si3（2120），V5Si3（2150），f區(qū)元素的硅化物在反應(yīng)堆中吸收中子。,2. +4 O.S. SiHal4，SiO2，Si3N4，SiC和SiH4 (1) Structure: 正四面體結(jié)構(gòu)單元: SiO4 , SiS4 , SiN4 ,SiC4 (2) properties: a. 與堿反應(yīng): SiO2 + Ca(OH)2 = CaSiO3 + H2O SiH4 + 2KOH + H2O = K2SiO3 + 4H2 CaS + SiS2 = CaSiS3,b. Hydrolysis (i) SiCl4 + 4H2O = H4SiO4 + 4HCl SiS2 + 4H2O = H4SiO4 + 2H2S (ii) SiF4 + 3H2O = H2SiO3 + 4HF 4HF + 2SiF4 = 2H2SiF6 即：3SiF4 + 3H2O = H2SiO3 + 2H2SiF6 (3) SiHal4制備 a. CaF2 + H2SO4 = CaSO4 + 2HF SiO2 + 4HF = SiF4 + 2H2O b. SiO2 + 2C + 2Cl2 = SiCl4 + 2CO,(4) 硅烷 SinH(2n+2) n可高達(dá)15 a. preparation: Mg2Si + 2H2SO4 = SiH4 + 2MgSO4 Mg2Si + 4NH4Br = SiH4 +2MgBr2 + 4NH3 SiCl4(l) + LiAlH4(s)= SiH4(g) + LiCl(s) + AlCl3(s) b. properties (i) reduction: SiH4 + 2KMnO4 = 2MnO2+ K2SiO3 + H2O + H2 可以用KMnO4來鑒別在純水中硅烷 (ii) hydrolysis: SiH4在純水和微酸性溶液中不水解，但在 微量堿作催化劑時(shí)，迅速水解生成硅酸與氫氣,H2O,NH3,Silicone rubber,(5) 硅酸(Silicic acid)及硅酸鹽 a. 可溶性酸鹽與H+ , CO2 , NH4+反應(yīng)得到H2SiO3 b. 硅酸鹽結(jié)構(gòu) (i) 每個(gè)SiO4四面體Si:O=1:4,化學(xué)式為SiO44- (ii) 兩個(gè)SiO4以角氧相連，Si和O的原子數(shù)之比是1:3.5，化 學(xué)式為Si2O72- (iii) SiO4以兩個(gè)角氧分別和其它SiO4兩個(gè)角氧相連成環(huán)狀或長鏈狀結(jié)構(gòu)，Si:O=1:3 (iv) SiO4以角氧構(gòu)造成雙鏈，SiO = 411， (v) SiO4分別以三角氧和其它三個(gè)SiO4相連成層狀結(jié)構(gòu) (vi) SiO4分別以四個(gè)氧和其他四個(gè)相連成立體結(jié)構(gòu)，SiO2,Si:O=1:3,14-3 Germanium Subgroup 一、General properties +4氧化態(tài)穩(wěn) Ge Sn Pb +2氧化態(tài)穩(wěn) 定性增大 定性增大 自然界中存在tinstone 錫石(SnO2)， galena (方 鉛礦) (PbS) 鉛存在于Uranium 和Thorium礦中，這是由于鉛是U和Th放射性衰變的產(chǎn)物,Pb可防alpha, gamma和X-ray但對beta和neutron效果差,二、The simple substances 1. Allotropes: 灰錫(錫) 白錫(錫) 脆錫 2. Properties: (1) Tin是兩性金屬 Sn + 2HCl = SnCl2 + H2 Sn + 2OH- + 2H2O = Sn(OH)42- + H2 (加熱) (2) Ge只有在H2O2（氧化劑）存在下，才溶于堿 Ge + 2KOH + 2H2O2 = K2 Ge(OH)6 ,13.6C 161 C,Pb也能與堿反應(yīng)： Pb + 2H2O + 2KOH = K2 Pb(OH) 4 + H2 (2) 與氧化性酸反應(yīng): a. Pb與任何濃度的硝酸反應(yīng)都得到Pb(NO3)2 b. Sn與濃HNO3反應(yīng)得到Sn(IV)，與稀HNO3反應(yīng)得 到Sn(II) 3Sn + 8HNO3 (稀)= 3Sn(