无机化学英文课件：05 group IA and IIA.pptx

alkali metal
Lithium, Sodium, Potassium, Rubidium and Cesium
The common metals of this group are sodium (% in the lithosphere, NaCl) and potassium (%, , carnallite光卤石).
Salt mines are considered to be good places to leave radioactive waste because they are not subject to groundwater flow - that is why the salt got left there in the first place!
NaOH, Na2CO3, Na2SO4, Na3P3O9 and Na4SiO4 are among the top 50 industrial chemicals.
Potassium salts, notable K2SO4 or KNO3, are an important component of fertilizer.
Lithium alkyls are important reagents in synthesis.
Na+ and K+ are very important physiological ions, and Li+ salts are used to treat certain mental disorders.
Except Li, the chemistry is predominantly that of the M+ ions. There may be a hint of covalency in certain chelate complexes.
Li+ would have a ratio of charge/radius similar to Mg2+ hence certain similarities.
Other "look alikes" are NH4+ which is similar to K+ and Tl+ which is a bit like Rb+ or Ag+.
How do the alkali metals react with water?
Reactions of the elements with water:
Group 1: M(s) + H2O(l)  M+(aq) + (OH)-(aq) + ½ H2(g)
Group 2: M(s) + 2 H2O(l)  M+2(aq) + 2 (OH)-(aq) + H2(g)
These reactions are very exothermic and increase in violence from the lightest to the heaviest elements in the group (enough to ignite the H2 for the heavier elements). The non-reversible nature of this reaction means that such metals are very useful for drying many kinds of solvents.
The s-block metals are used as reducing agents for an immense number of different types of compounds.
More generally:
Group 1: M(s) + HOR  M+ + (OR)- + ½ H2(g)
Group 2: M(s) + 2 HOR  M+2 + 2 (OR)- + H2(g)
These reactions make metal alkoxides that are very useful for the synthesis of other products using metathesis reactions. Metathesis indicates that the reagents exchange ligands with one another. Such reactions are especially favourable when it produces a metal halide because