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
Colors of carbonates formed by group 2 metals
All formed carbonates are white.
Solubility of Group 2 nitrates
All group 2 nitrates are soluble in water.
Solubility of Group1 salts
All salts of group1 are soluble except some Li salts such as PO42-, F, CO32-
Solubility of group 2 carbonates and phosphates
All are insoluble
Solubility of group 2 hydroxides
From Mg to Ba solubility increases Mg - IS Ca - SS Sr - SS Ba - aq
Solubility of group 2 Sulfates
From Mg - Ba solubility decreases Mg - aq Ca - SS Sr - IS Ba - IS
Solubility of group 2 Sulfites
Except Mg all others are insoluble while Mg is sparingly soluble
Solubility of group 2 chromates
Mg, Ca - aq
Sr, Ba - IS
Solubility of group 2 oxalates
Mg, Ba - SS
Ca, Sr - IS
Which has largest ionic radii in water?
Li
Basicity of s block elements depends on
Depends on the electropositivity of the elements
Higher the electropositivity higher the basic character
Lower the ionization energy higher the electropositivity
Ionic radii in water of s block elements
Smaller the cationic radius larger the ionic radii in water
Reactivity with hydrogen
Lower the difference between the anionic radius and the cationic radius higher will be the stability
Elements tends to from stable compounds so that the reactivity increases.
Metallic nature
Metallic character depends onthe ability of an element to lose its outer valence electrons.
Across a period from left to right metallic nature decreases while down the group it increases.
Basic nature of hydroxides
Lower the bond strength higher will be the basic nature
Thermal stability
Thermal stability 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.
Solubility depends on
Solubility depends on the radii difference between the anion and cation
Higher the difference higher the solubility
Melting points of s and p block elements
Boiling points of metals increases from left to right as the metallic bond strength increases due to the decrease in cationic radius.
14th group elements like carbon and silicon will have the highest melting points due to the formation of covalent bond network structures.
From 15th to 16th group boiling point increases and from 17th to 18th group boiling point decreases
Na2O(s)-Nature, oxidation no and bonding type
Strongly basic
+1
Ionic
MgO(s)-Nature, oxidation no and bonding type
Basic
+2
Ionic
Al2O3(s)-Nature, oxidation no and bonding type
Amphoteric
+3
Ionic
SiO2(s)-Nature, oxidation no and bonding type
Very weakly acidic
+4
Covalent bond network
P4O10(s)-Nature, oxidation no and bonding type
Weakly acidic
+5
Covalent
SO3(g)-Nature, oxidation no and bonding type
Acidic
+6
Covalent
Cl2O7(l)-Nature, oxidation no and bonding type
Strong acid
+7
Covalent
SiO2(s) + 2NaOH(aq)
Na2SiO3(aq) + H2O
P4O10(s) + 6H2O(l)
4H3PO4(aq)
SO3(g) + H2O(l)
H2SO4(aq)
Cl2O7 (l) + H2O(l)
2HClO4(aq)
P4O10(s) + 12NaOH(aq)
4Na3PO4(aq) + 6H2O(l)
SO3(g) + 2NaOH(aq)
Na2SO4(aq) + H2O(l)
Cl2O7 (l) + 2NaOH
2NaClO4(aq) + H2O(l)
H2S(g) + H2O(l)
HS ̶ (aq) + H3O+(aq)
HCl(g) + H2O(l)
Cl ̶ (aq) + H3O+(aq)
NaH(s)-Nature, oxidation no and bonding type
Strongly basic
+1
Ionic
MgH2(s)-Nature, oxidation no and bonding type
Weakly basic
+2
Ionic
AlH3(s)-Nature, oxidation no and bonding type
Amphoteric
+3
Network covalent
SiH4(g)-Nature, oxidation no and bonding type
Very weakly acidic
-4
Covalent
PH3(g)-Nature, oxidation no and bonding type
Neutral
-3
Covalent
HCl(g)-Nature, oxidation no and bonding type
Very strongly acidic
-1
Covalent
H2S(g)-Nature, oxidation no and bonding type
Weakly acidic
-2
Covalent
SiCl4(l) + 2H2O(l)
SiO2(s) + 4HCl(aq)
PCl5(g) + 4H2O(l)
H3PO4(aq) + 5HCl(aq)
2SCl2(g) + 3H2O(l)
H2SO3(aq) + S(s) + 4HCl(aq)
NaCl(s)-Nature, oxidation no and bonding type
Neutral
+1
Ionic
MgCl2(s)-Nature, oxidation no and bonding type
Very weakly acidic
+2
Ionic
AlCl3(s)-Nature, oxidation no and bonding type
Acidic
+3
Covalent
SiCl4(l)-Nature, oxidation no and bonding type
Acidic
+4
Covalent
PCl5(g)-Nature, oxidation no and bonding type
Acidic
+5
Covalent
SCl2(g)-Nature, oxidation no and bonding type
Acidic
+2
Covalent