Alkali metals презентация

INTRODUCTION
Name of this family comes from the properties of alkali metals to form hydroxides with water. Compounds containing hydroxide ion is basic and called alkali.

They are very active ,so in the nature they are not found in elemental forms. They exist in various compounds.

reactions, they form +1 charged ions.
* Alkali metals are the elements which have the least ionization energy and the highest atomic radius, in each period
* They are a group of most active metals.
* The activity of metals increase from top to bottom
* The element cesium, Cs, is the most active metal
* Francium is a radioactive element

be cut by a knife.

Na

not found free in nature, but as compounds.
Sodium, Na
The most important compound of sodium is sodium chloride, NaCl. The important sodium sources are Chile saltpeter (NaNO3), washing soda (Na2CO3) and baking soda (NaHCO3). The most important sodium minerals are kryolite (Na3AlF6), borax (Na2B4O7.10H2O), sodium sulfate (Na2SO4) and albite (NaAlSi3O8).

as the minerals sylvite (KCl) and carnallite (KCl · MgCl2 ·6H2O) and as the silicates of orthoclas (KAlSi3O8) and mica (KH2Al3(SiO4)3). The main sources of potassium are K2SO4 and KNO3, which are used as fertilizers.

nM0 + Y+n → nM+ + Y0(s)
(Y : any metal with low activity,
M : any alkali metal)
 
0 +3 +1 0
6Na(s) + Al2O3(s) → 3Na2O(s) + 2Al(s)
 
0 +3 +1 0
3K(s) + CrCl3(s) → 3KCl(s) + Cr(s)

with hydrogen. Hydrides contain a +1 charged alkali metal and –1 charged hydrogen

2K(s) + H2(g) ⎯→ 2KH(s) potassium hydride

2Na(s) + H2(g) ⎯→ 2NaH(s) sodium hydride

reaction H2 gas and a base solution form.

2M(s) + 2H2O(l) → 2MOH(aq) + H2(g) +heat

2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) + heat

oxygen in the air.
As a result of reactions with excess oxygen, lithium forms oxide, Li2O, sodium forms peroxide Na2O2 and potassium, rubidium and cesium form superoxides, such as KO2, RbO2, CsO2.
4Li(s) + O2(g) ⎯→ 2Li2O(s)
2Na(s) + O2(g) ⎯→ Na2O2(s)
K(s) + O2(g) ⎯→ KO2(s)

(salts of alkali metals).
2M(s) + X2(g) ⎯→ 2MX(s)
(M : alkali metal, X : halogen,
MX ; alkali metal halides)
2Li(s) + F2(g) ⎯→ 2LiF(s)
2Na(s) + Cl2(g) ⎯→ 2NaCl(s)

No reaction
7. When they react with acids, the produce salts andliberate H2 gas.
M(s) + HX(aq) ⎯→ MX(aq) + 1/2H2(g)
(HX : Halo acid, MX : salt of an alkali)
2K(s) + 2HCl(aq) ⎯→ 2KCl(aq) + H2(g)
2Na(s) + 2HBr(aq) ⎯→ 2NaBr(aq) + H2(g)