S Block Elements Flashcards
Group1 elements trends
Alikaline metals
They are soft metals having a low density
Highly reactive metals and reactivity incrrases down the group.
Reactions with oxygen
Group 1 metals
Generally forms the metal oxide
Na produces peroxides with excess oxygen
K, Rb, Cs produces superoxides with excess oxygen
Reactions with air
Group 1 metals
With nitogen Li gives Li3N, K,Na does not react with N2
When K is burnt in air, KO2 is produced as the main product while peroxides and oxides are also formed.
Na2O(s) + H2O(l)
2NaOH(aq)
Li3N(s) + 3H2O(l)
3LiOH(aq) + NH3(g)
2NaOH(aq) + CO2(g)
Na2CO3(aq) + H2O(l)
2Na(s) + H2(g)
2NaH(s)
NaH(s) + H2O(l)
NaOH(aq) + H2(g)
2Li(s) + dil. 2HNO3(aq)
2LiNO3(aq) + H2(g)
2Na(s) + dil. H2SO4(aq)
Na2SO4(aq) + H2(g)
4LiNO3(s)
2Li2O(s) + 4NO2(g) + O2(g)
2KNO3(s)
2KNO2(s) + O2(g)
General reaction for all other group 1 metal nitrates except Li(diagonal relationship with Mg)
Li2CO3(s)
Li2O(s) + CO2(g)
Less stable and gets decomposed easily.
Other group 1 carbonates are stable and they will melt before getting decomposed.
2NaHCO3(s)
Na2CO3(s) + H2O(g) + CO2(g)
General reaction for group 1 metals.
Solubility of Group 1 salts
All Group 1 salts are soluble in water except some lithium salts such as LiF, Li2CO3 and
Li3PO4. All these salts are white solids unless the salt anion is a coloured ion.
Solubility of Group 1 halides increase down the group
Flame test- Lithium
– Crimson red
Flame test- Sodium
Yellow
Flame test- Rubidium
Red-violet
Flame test- Caesium
Blue-violet
Flame test- Potassium
Lilac
Group 2 elements trends
They are known as alkaline earth metals. They are less reactive than Group 1 metals due to its valence shell ns2
electron configuration.
Group 2 metal oxides produce basic oxides except for BeO which shows amphoteric properties.
Reaction with water
Group 2 metals
Beryllium does not react with water, but it reacts with steam. The reaction of magnesium
with water at room temperature is negligible. However, magnesium reacts slowly with
hot water. Calcium, strontium and barium react readily with cold water.
Ca(s) + 2H2O(l)———-> Ca(OH)2(aq) + H2(g)
Ca(s) + H2(g)
CaH2(s)
CaH2(s) + 2H2O(l)
Ca(OH)2(aq) + 2H2(g)
3Mg (s) + N2(g)
Mg3N2(s)
Mg3N2(s) + 6H2O(l)
3Mg(OH)2(aq) + 2NH3(g)
2Mg(NO3)2(s)
2MgO(s) + 4NO2(g) + O2(g)
Behaves similar to LiNO3
All nitrates are soluble in water.
MCO3
MO + CO2
Thermal stability of group 2 metals increases down the group.
When going down the group the polarizing power of the cation decrease resulting in a less polarized anion.
Less the polarization of the anion more the thermal stability.
Ca(HCO3)2(aq)
CaCO3(s) + CO2(g) + H2O(l)
Flame test- Calcium
Orange-red
Flame test- Strontium
Crimson red
Flame test- Barium
Yellowish green