无机化学(张天蓝)fe.ppt
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1、1,Chap 19 Iron,Hematite A mineral form of Fe2O3,2,A periodic table of partial ground-state electron configurations,d block elements,4,掌握溶液中铁离子的水解,聚合和沉淀 掌握溶液中铁离子的氧化还原及其生物效应 掌握溶液中铁离子的配位化学及其生物效应 了解铁在生物体内的性质和功能,5,铁的化学符号Fe 铁的英文名称是Iron,The name of Iron,青铜时代公元前两千年 青铜向铁器过度时代公元前一千年 铁器时代公元前一千年后 我国使用铁、钢春秋战国之交时
2、期,6,Iron in our life,7,d区元素在周期表中的位置, Fe Co Ni 3d64s2 3d74s2 3d84s2 价态:+2 +3 (+6) +2 +3 (+5) +2 +3 (+4),8,Review,9,Hard and Soft Acids and Bases,Hard acids are small, usually highly charged.Their electron cloud is not readily polarisable.,Hard Bases contain the larger electronegative atoms, especiall
3、y O, N, F and Cl. These donor atoms also have rather unpolarisable electron clouds,离子键,Alkali metals (Li+, Na+, ),Alkali earth metal (Mg2+, Ca2+, ),Lighter transition metals in their higher oxidation states: Ti(IV), Ti(III), Cr(III), Fe(III), Co(III) ,Al3+,10,Soft acids- are larger metal ions, often
4、 in their lower oxidation states. Their electron cloud is readily polarisable.,Soft Bases- contain the larger, more polarisable and less electronegative atoms, especially S, Se, P, C and As.,Hard and Soft Acids and Bases,Heavier transition metals (Pt, Rh, Ir),Transition metals in their lower oxidati
5、on state Cu(I), Ag(I), Hg(I), Hg(II), Pd(II), Pt(I), Pt(II),H- (hydride),C donors,S, P, As donors,I-,11,Table showing distribution of hard, soft, and intermediate Lewis Acids in the Periodic Table, largely after Pearson.,Hard and Soft Acids and Bases,12,13,Pearsons Hard and Soft Acids and Bases,Hard
6、 Lewis acids prefer to bind to hard Lewis bases; soft Lewis acids prefer to bind to soft Lewis bases,14,The properties of of Iron ion,铁的溶液化学,15,Hydrolysis is a reaction that dissociates water,H3O+,16,Review,Factors that control the acidity of metal ions in aqueous solution:,1) The smaller the metal
7、ion, the more acidic it will be. Metal ion: Be2+ Mg2+ Ca2+ Sr2+ Ba2+ pKa: 5.6 11.4 12.7 13.2 13.4 2) The higher the charge on metal ions of about the same size, the more acidic will the metal ion be:,Metal ion: Na+ Ca2+ La3+ Th4+ Ionic radius (): 1.02 1.00 1.03 0.94 pKa: 14.1 12.7 8.5 3.2,17,metal i
8、on forms stronger M-O bond and pulls electron density from the O-H bond,reduced electron density in O-H bond leads to easier loss of a proton:,3) metal ions of higher electronegativity will be much more acidic than metal ions of similar size and charge, but of low electronegativity,Hydration increas
9、es with increasing charge/size ratio and electronegativity of the metal ions.,18,If metal is able to polarise the M-O bond towards it,that will cause the H-O bond to be polarised towards O,releasing H+ to be accepted by a Lewis base.,Hydratation,hydrolysis, polymerization, precipitation,19,Aqua acid
10、s are in principle polyprotic acids,Fe(OH2)63+,etc.,水解是分散电荷的方式,鲍林的电中性原理- 稳定的分子是每个原子的净电 荷接近于零,或+11之间。,Fe(OH2)63+ - exists in strongly acidic solution,20,Fe(H2O)63+ Fe(OH)(H2O)52+H+ K1=10-3.05 淡紫,Fe(OH)2(H2O)4+H+,Fe(OH)3,, ,结构,Fe3+水解最终产物:Fe(OH)3,Hydrolysis of Fe3+ ions,水中为水合铁离子双聚体,21,Hydrolysis increa
11、ses with increasing charge/size ratio of the metal ions.,Fe(H2O)62+ Fe(OH)(H2O)5+H+ K=10-9.5 淡绿,Fe(H2O)63+ Fe(OH)(H2O)52+H+ K1=10-3.05 淡紫,Hydrolysis of Fe2+ ions,22,控制溶液的pH,降低铁的总浓度,加入结合铁的物质(包括能够与铁离子配位结合的配体),How to deal with hydratation, polymerization, precipitation?,Fe(H2O)62+ Fe(OH)(H2O)5+H+ K=10-
12、9.5 淡绿,23,1、口服铁剂时应将药物放在舌面上,直接用水冲饮下肚,不要咀嚼药物. 2、同时服用或果汁 3、含钙类食品(如豆腐)和高磷酸盐食品(如牛奶)等故应避免合用。 口服铁剂期间,不要喝浓茶或咖啡。,口服补铁药时该注意,24,?,Eocell 0, spontaneous; Eocell 0, non-spontaneous.,Recall 1: Determining the direction of reaction,25,Fe3+和Fe2+在水溶液中的氧化还原 (pH的影响),从标准电极电势看Fe3+和Fe2+在水溶液的稳定性,Fe3+ e Fe2+ E =0.77V,O2 4H
13、+ 4e H2O E=1.229V,2 H+ 2e H2 E = 0 V,Fe3+和Fe2+二者在水溶液中都相对稳定,含氧的水溶液里,Fe3+和Fe2+离子虽然都能够稳定存在,但是Fe3+是稳定的,而Fe2+离子是亚稳定的,O2 4H+ 4e H2O E=1.229V,Fe3+ e Fe2+ E =0.77V,26,Nernst equation of electrode potential,在非标准状态下, 电极电势与标准电极电势之间的关系式为,纯固体、纯液体及溶剂不列入方程中 1 气体物质用相对分压P/P表示 电极反应中有H+或OH-等参加,其浓度也必须列入,Recall 2,27,MLn
14、n+e MLn (n1)+ ,配位化合物调节还原电势,根据奈斯特方程式:,28,29,An intro to electron transport chains,铁催化生物氧化 (配体的影响),30,Electron transport and chemiosmotic generation of ATP,In eukaryotic cell,細胞色素氧化酶複合物,细胞内的线粒体是生物氧化的主要场所,呼吸链(respiratory chain)又称电子传递链(electron transfer chain)代谢物脱下的成对氢原子(2H)通过多种酶和辅酶所催化的连锁反应逐步传递,最终与氧结合生成
15、水,31,Mitochondria are the major source of intracellular ROS production due to electron transport,Protein,Heme 血红素,Iron,Cytochrome (细胞色素) Structure,32,细 胞 色 素,33,MLnn+e MLn (n1)+ ,配位化合物调节还原电势,根据奈斯特方程式:,34,Consider the oxidation of Cyt b by Cyt c1.,Cyto b-Fe2+ + Cyt c 1-Fe3+ Cyto b-Fe3+ + Cyto c 1 -Fe
16、2+,G 0,With Nernst equation: G0 = -nF E0, E0 = E01 - E02 0,e,35,Application in the process, E0 = E0red - E0ox = 0.22 V - 0.077 V = 0.143 V. G = -nF E 0 = -(1)(96.48 kJ/V-mol)(0.143V) = -42.39 kJ/mol Therefore this process is spontaneous,Sum: Cyto b-Fe2+ + Cyt c1 -Fe3+ Cyto b-Fe3+ + Cyto c1 -Fe2+,36,
17、37,Free energy change during electron transport,G 0, G0 = -nF E0, E0 = E01 - E02 0,electron transport chain and the drop in free energy as electrons travel down the chain,38,原子在形成分子时,分子中的电子在整个分子空间 范围内运动, 分子轨道是原子轨道的波函数的线性组合 几个原子轨道可组合成几个分子轨道,在分子中电子的 空间运动状态可用相应的分子轨道波函数来描述。 其中一半为成键分子轨道 :、 ; 另一半为反键分子轨道 :
18、 *、* 。,分子轨道要点, 分子中电子运动的整体性:,分子轨道(molecular orbital): 描述分子中电子运动的波函数,指具有特定能量的某电子在相互键合的两个或多个原子核附近空间出现概率最大的区域,Recall 3:,39,H2 中的分子轨道,I = C1a+ C2b II = C1aC2b,40,Molecular Orbital of Triplet Oxygen,复习:,.O2-,O22-,O2,41,3O2 KK (s2s)2(s*2s)2 (s2px)2 (p2py)2 (p2pz)2(p*2py)1 (p*2pz)1 .O2- KK (s2s)2(s*2s)2 (s2
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