s block Flashcards
MP trend in s block
grp 1: MP decreases down grp regularly
grp 2 : Mg has lowest MP for rest it decreases down regularly
BP trend in s block
grp 1: BP decreases down grp regularly
grp 2: BP decreases till Sr then increases.
Mg has lowest BP.
(due to weak cohesive force)
Density trend in s block
Density increases down the group(K has exceptionally low density, due to large at. vol)
[Li<K<Na<Rb<Cs]
grp 2:Density decreases till Ca then increases.
[Ca<Mg<Be<Sr<Ba]
Relation between hydration energy and reducing character
Higher the hydration energy better is the reducing character.
Which is the best RA in the group?
Li has highest hydration energy in all of periodic table (best RA in all of periodic table
Li
carmine yellow
Na
golden yellow
L
voilet (lilac)
Ba
apple green
Ca
brick red
Sr
crimson red
Rb
ruby violet
Cs
blue
oxide formation
Li forms monoxides and Na forms peroxide. rest metals forms superoxide.
tendency to form superoxide increases down the group since larger cation balances larger anion.
solubility of alkali halides
Li is less soluble doe to high lattice energy.
rest halides are solube in organic solvent
heating effect (IMP)
Be and Mg undergo hydrolysis on heating whereas other metals undergo dehydration
Carbonates
grp 1: except Li all other metals forms thermally stable carbonates
grp 2: insoluble carbonates, solubility decreases down the group.
BeCO3 is unstable can only be stored in atmosphere of oxygen
bicarbonates existence in solid state
Li bicarbonate doesnt exist in solid state .
NaHCO3- polymer
KHCO3- dimer
nitrates on heating
grp 1: except Li all form MNO2 and O2. Li forms Li2O, NO2, O2
soln in liq. ammonia
both form deep blue solution. colour id due to solvated ammonium electrons
lepidolite
Li2Al2(SiO3)3(FOH)2
borax
Na2B4O7.10H2O
saltpetre
NaNO3
sylvinite
NaCl
Sylvite
KCl
carnalite
KCl.MgCl2.6H2O
Li uses
1) Li stearate used in automobile grease
2) Li2CO3 is added in bauxite in electrolytic production of AL as it lowers mp
3) to toughen glass
4) used for making electrochemical cells
Na uses
1) Caustic soda NaOH (imp alkali) used for making organic and inorganic compounds, paper making
2) Soda ash Na2CO3 soap making
3) NaHCO3 is used in baking powder
K uses
1) fertilizers
2)KNO3 explosive
3) KMnO4 used in manufacture os sacchrine and as OA
4) K2CO3 ceramics, colour tv
5) KO2 used in breathing apparatus in submarines
6) KBr used in photography
miscibilty of Li
due to small size lithium is miscible with an above 380 but is immiscible with others. others are miscible with each other in all propotions
