17、 appears that any crown with CH2CH2 bridges prefers K+ because of the 5-membered chelate ring size rather than the size of the hole on the crown - the macrocycle just puckers up to fit, but solvent effects may also be very important,Cryptands and Cryptates,Cryptands are polycyclic cages, usually inc 。

18、luding nitrogen as well as oxygen to get the necessary junctions. Metal ions are encapsulated even more securely inside them leading to cryptates,Reaction with Cryptands,2 Na Na+ + Na- When crypt-222 is added to ethylamine solution of Na, isolated product is Na(crypt-222)+Na-. Golden yellow, diamagn 。

19、etic solid. Na- : sodide Cs(crypt-222)+e- Black, electride,Some remarkable compounds have been made: 2Na(NEt3)+2,2,2-crypt,Na(2,2,2-crypt)+Na-(s,Bear in mind that: 2Na Na+Na-H = 438 kJ mol-1,alkaline earth metal,Beryllium, Magnesium, Calcium, Strontium and Barium,Sources,Beryllium is found in the mi 。

20、neral beryl(绿柱石), Be3Al2(SiO3)6. Beryl with around 2.9% Cr3+ substituting for Al3+ is emerald(祖母绿). Beryllium compounds are dangerously toxic and can pass through the skin - care! The other elements are fairly common in a variety of minerals e.g. limestone, CaCO3, dolomite (白云石), CaCO3.MgCO3 and car 。

21、nallite, KCl.MgCl(6H2O). Less common are strontianite(菱锶矿), SrCO3, and barytes(重晶石), BaCO3. Radium, the bottom member of the group is radioactive with a half-life (226Ra)of about 1600 years as -emitter. It was first isolated from uranium ore, pitchblende(沥青铀矿), by M. and P. Curie, by laborious fract 。

22、ional crystallizations,Beryllium,obtained by the reduction of BeCl2 by Ca or Mg or the Mg reduction of BeF2. a very light metal, unreactive with air or water at ordinary temperatures. dissolves in strong non-complexing acids (except HNO3 which passivates it) to give the Be(H2O)42+ ion. Be also disso 。

23、lves in strong aqueous bases like NaOH to evolve hydrogen and yield the beryllate, Be(OH)42- ion. Its amphoteric behavior is similar to aluminum,Properties of Be Compounds,Beryllium compounds are fairly covalent and the chemistry is dominated by the Be attempting to obtain an octet The simple Beryll 。

24、ium compounds can react with Lewis bases forming, for example, BeCl2(OEt2)2, and complex anions are also formed e.g. BeF42-, and Be(H2O)42+. Polymerization occurs through bridging groups to give chain polymers, e.g. (BeF2)n, (BeCl2)n and (Be(CH3)2)n. In the halides, the bridges are not electron defi 。

25、cient, but in the alkyls, three-centre, two-electron bonds must be invoked. For bulkier groups, for example certain alkoxides, the chain lengths can be reduced, or polymerization can even be inhibited,Basic beryllium acetate,Be4O(CH3CO2)6, which is soluble in nonpolar solvents e.g. benzene, has a te 。

26、trahedral arrangement of Be atoms around the oxygen atom, and an acetate bridging each of the six edges of the tetrahedron,Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water,AN OVERVIEW OF PHOTOSYNTHESIS,Carbondiox 。

27、ide,Water,Glucose,Oxygengas,PHOTOSYNTHESIS,THE OXYGEN EVOLVING CENTER,THE TYROSINE RADICAL BRIDGES THE WATER MOLECULE AND THE CHLOROPHYLL MOLECULE,Chlorophyll a & b,Chl a has a methyl group Chl b has a carbonyl group,Photosynthesis uses light energy to make food molecules,Light,Chloroplast,Photosyst 。

28、em IIElectron transport chains Photosystem I,CALVIN CYCLE,Stroma,Electrons,LIGHT REACTIONS,CALVIN CYCLE,Cellular respiration,Cellulose,Starch,Other organic compounds,A summary of the chemical processes of photosynthesis,One of the most important discoveries in synthetic chemistry was made by Victor。

29、Grignard (Nobel Prize 1912) following the initial work of others. He showed that the reaction of Mg with organic iodides (RI, later applied to other halides) results in the insertion of the Mg into the R-I bond. This provides a reagent of the form R-Mg-I that can be used in nucleophilic or metathesi 。

【IIA无机化学|无机化学英文课件：05 group IA and IIA】30、s reactions to make new carbon-carbon bonds,Analogous and more reactive reagents can be made with Li and Na,Mg(s) + R-I R-Mg-I R-Mg-I + I-R R-R + MgI2,2 Li(s) + R-X R-Li + Li-X (X = halide) R-Li + X-R R-R + Li-X,Such compounds were among the first that were recognized to contain bonds between metals and carbon. These were thus some of the initial examples of organometallic chemistry (one of the most studied branches of inorganic chemistry today,Cp*2Mg,Cp*NaTHF 。

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标题：IIA无机化学|无机化学英文课件：05 group IA and IIA( 二 )