Important S-Block Element Formulas for JEE and NEET

 Page 1


  
s-BLOCK ELEMENTS & THEIR COMPOUNDS
Group 1 of the periodic table consists of the elements : lithium, sodium,
potassium, rubidium, caesium and francium .
The elements of Group 2 include beryllium, magnesium, calcium, strontium,
barium and radium.
Hydration Enthalpy :
The hydration enthalpies of alkali metal ions decrease with increase in
ionic sizes.Li
+
 has maximum degree of hydration and for this reasons
lithium salts are mostly hydrated e.g., LiCl . 2H
2
O
Physical properties :
All the alkali metal are silvery white, soft and light metals. Because of the
larger size, these element have low density. The melting and boiling point
of the alkali metals  are low indicating weak metallic bonding alkali metals
and their salts impart characteristic colour to an oxidizing flame.
Metal Li Na K Rb Cs
Colour Crimson
red
Yellow
Violet/
Lilac Red
violet
Blue
Chemical Properties:
The alkali metal are highly reactive due to their larger size and low ionization
enthalpy.
?   Reactivity towards air : They burn vigorously in oxygen forming
oxides. Lithium forms monoxide, sodium forms peroxide, the other metals
form superoxide.
?  Reducing nature: The alkali metals, are strong reducing agents,
lithium being the most and sodium the least powerful.
?  Solution in liquid ammonia: The alkali metals dissolve in liquid
ammonia giving deep blue solution which are conducting in nature.
M+ (x + y) NH
3
 ?? ? ?[M(NH
3
 )
x
 ]
+
 + [e(NH
3
)
y
]
?
The blue colour of the solution is due to the ammoniated electron and the
solutions is paramagnetic.
M
+
(am)
 
+ e
?
 + NH
3
 (?) ? ? ? ? ? ? ?
ding tan s on
 MNH
2
(am) + 1/2 H
2
(g)
In concentrated solution, the blue colour changes to bronze colour and
becomes, diamagnetic.
Page 2


  
s-BLOCK ELEMENTS & THEIR COMPOUNDS
Group 1 of the periodic table consists of the elements : lithium, sodium,
potassium, rubidium, caesium and francium .
The elements of Group 2 include beryllium, magnesium, calcium, strontium,
barium and radium.
Hydration Enthalpy :
The hydration enthalpies of alkali metal ions decrease with increase in
ionic sizes.Li
+
 has maximum degree of hydration and for this reasons
lithium salts are mostly hydrated e.g., LiCl . 2H
2
O
Physical properties :
All the alkali metal are silvery white, soft and light metals. Because of the
larger size, these element have low density. The melting and boiling point
of the alkali metals  are low indicating weak metallic bonding alkali metals
and their salts impart characteristic colour to an oxidizing flame.
Metal Li Na K Rb Cs
Colour Crimson
red
Yellow
Violet/
Lilac Red
violet
Blue
Chemical Properties:
The alkali metal are highly reactive due to their larger size and low ionization
enthalpy.
?   Reactivity towards air : They burn vigorously in oxygen forming
oxides. Lithium forms monoxide, sodium forms peroxide, the other metals
form superoxide.
?  Reducing nature: The alkali metals, are strong reducing agents,
lithium being the most and sodium the least powerful.
?  Solution in liquid ammonia: The alkali metals dissolve in liquid
ammonia giving deep blue solution which are conducting in nature.
M+ (x + y) NH
3
 ?? ? ?[M(NH
3
 )
x
 ]
+
 + [e(NH
3
)
y
]
?
The blue colour of the solution is due to the ammoniated electron and the
solutions is paramagnetic.
M
+
(am)
 
+ e
?
 + NH
3
 (?) ? ? ? ? ? ? ?
ding tan s on
 MNH
2
(am) + 1/2 H
2
(g)
In concentrated solution, the blue colour changes to bronze colour and
becomes, diamagnetic.
  
ANOMALOUS PROPERTIES OF LITHIUM
(i) exceptionally small size of its atom and ion, and (ii) high polarising
power (i.e., charge/ radius ratio ).
The similarity between lithium and magnesium is particularly striking and
arises because of their similar size: atomic radii, Li = 152 pm, Mg = 160
pm; ionic radii : Li
+
 = 76 pm, Mg
2+
 = 72 pm.
GROUP 2 ELEMENTS : ALKALINE EARTH METALS
The first element beryllium differs from the rest of the member and shows
diagonal relationship to aluminium.
Hydration Enthalpies
Hydration enthalpies of alkaline earth metal ions. Be
2+
 > Mg
2+
 > Ca
2+
 >
Sr
2+
 > Ba
2+
. The hydration enthalpies of alkaline earth metal ions are larger
than those of alkali metal ions.  Thus, compounds of alkaline earth metals
are more extensively hydrated than those of alkali metals , e.g., MgCl
2
and CaCl
2
 exist as MgCl
2 
.6H
2
O and CaCl
2
. 6H
2
O while NaCl and KCl do
not form such hydrates.
Physical Properties
The alkaline earth metals, in general, are silvery white, lustrous and relatively
soft but harder than the alkali metals. The melting and boiling point of
these metals are higher due to smaller sizes. Because of the low ionisation
enthalpies they are strongly electropositive in nature. The electrons in
beryllium and magnesium are too strongly bound to get excited by flame.
Hence these elements do not impart any colour to the flame.
Calcium, strontium and barium impart characteristic colour to the flame.
Metal Be Mg Ca Sr Ba
Colour No 
colour
No 
colour
Brick
red
Crimson Apple 
green
Chemical Properties
?  Reactivity towards air and water :  Beryllium and magnesium are
inert  to oxygen and water. Magnesium is more electropositive and burns
with dazzling brilliance in air to give MgO and Mg
3
N
2
 .Calcium, strontium
and barium are readily attacked by air to form the oxide and nitride.
,
?  Reducing nature : The alkaline earth metals are strong reducing
agent. This is indicated by large negative value of their reduction potentials.
,
Page 3


  
s-BLOCK ELEMENTS & THEIR COMPOUNDS
Group 1 of the periodic table consists of the elements : lithium, sodium,
potassium, rubidium, caesium and francium .
The elements of Group 2 include beryllium, magnesium, calcium, strontium,
barium and radium.
Hydration Enthalpy :
The hydration enthalpies of alkali metal ions decrease with increase in
ionic sizes.Li
+
 has maximum degree of hydration and for this reasons
lithium salts are mostly hydrated e.g., LiCl . 2H
2
O
Physical properties :
All the alkali metal are silvery white, soft and light metals. Because of the
larger size, these element have low density. The melting and boiling point
of the alkali metals  are low indicating weak metallic bonding alkali metals
and their salts impart characteristic colour to an oxidizing flame.
Metal Li Na K Rb Cs
Colour Crimson
red
Yellow
Violet/
Lilac Red
violet
Blue
Chemical Properties:
The alkali metal are highly reactive due to their larger size and low ionization
enthalpy.
?   Reactivity towards air : They burn vigorously in oxygen forming
oxides. Lithium forms monoxide, sodium forms peroxide, the other metals
form superoxide.
?  Reducing nature: The alkali metals, are strong reducing agents,
lithium being the most and sodium the least powerful.
?  Solution in liquid ammonia: The alkali metals dissolve in liquid
ammonia giving deep blue solution which are conducting in nature.
M+ (x + y) NH
3
 ?? ? ?[M(NH
3
 )
x
 ]
+
 + [e(NH
3
)
y
]
?
The blue colour of the solution is due to the ammoniated electron and the
solutions is paramagnetic.
M
+
(am)
 
+ e
?
 + NH
3
 (?) ? ? ? ? ? ? ?
ding tan s on
 MNH
2
(am) + 1/2 H
2
(g)
In concentrated solution, the blue colour changes to bronze colour and
becomes, diamagnetic.
  
ANOMALOUS PROPERTIES OF LITHIUM
(i) exceptionally small size of its atom and ion, and (ii) high polarising
power (i.e., charge/ radius ratio ).
The similarity between lithium and magnesium is particularly striking and
arises because of their similar size: atomic radii, Li = 152 pm, Mg = 160
pm; ionic radii : Li
+
 = 76 pm, Mg
2+
 = 72 pm.
GROUP 2 ELEMENTS : ALKALINE EARTH METALS
The first element beryllium differs from the rest of the member and shows
diagonal relationship to aluminium.
Hydration Enthalpies
Hydration enthalpies of alkaline earth metal ions. Be
2+
 > Mg
2+
 > Ca
2+
 >
Sr
2+
 > Ba
2+
. The hydration enthalpies of alkaline earth metal ions are larger
than those of alkali metal ions.  Thus, compounds of alkaline earth metals
are more extensively hydrated than those of alkali metals , e.g., MgCl
2
and CaCl
2
 exist as MgCl
2 
.6H
2
O and CaCl
2
. 6H
2
O while NaCl and KCl do
not form such hydrates.
Physical Properties
The alkaline earth metals, in general, are silvery white, lustrous and relatively
soft but harder than the alkali metals. The melting and boiling point of
these metals are higher due to smaller sizes. Because of the low ionisation
enthalpies they are strongly electropositive in nature. The electrons in
beryllium and magnesium are too strongly bound to get excited by flame.
Hence these elements do not impart any colour to the flame.
Calcium, strontium and barium impart characteristic colour to the flame.
Metal Be Mg Ca Sr Ba
Colour No 
colour
No 
colour
Brick
red
Crimson Apple 
green
Chemical Properties
?  Reactivity towards air and water :  Beryllium and magnesium are
inert  to oxygen and water. Magnesium is more electropositive and burns
with dazzling brilliance in air to give MgO and Mg
3
N
2
 .Calcium, strontium
and barium are readily attacked by air to form the oxide and nitride.
,
?  Reducing nature : The alkaline earth metals are strong reducing
agent. This is indicated by large negative value of their reduction potentials.
,
  
?  Solution in liquid ammonia: The alkaline earth metals dissolve in
liquid ammonia to give deep blue black solution forming ammoniated ions.
M + (x + y) NH
3
 ? [ M(NH
3
)
x
]
2+ 
+ 2 [e(NH
3
)
Y
 ]
?
From these solutions, the ammoniates, [M(NH
3
)
6
]
2+
 can be recovered.
ANOMALOUS BEHAVIOUR OF BERYLLIUM
Beryllium the first member of the Group 2 metals, shows
anomalous behaviour as compared to magnesium and rest of the members.
Further, it shows diagonal relationship to aluminium.
Diagonal Relationship between Beryllium and Aluminium
The ionic radius of Be
2+
 is estimated to be 31 pm; the charge/
radius ratio is nearly the same as that of the Al
3+
 ion. Hence beryllium
resembles aluminium in some ways.
Compounds of s-block elements :
1. Sodium Oxide (Na
2
O) :
2. Sodium peroxide (Na
2
O
2
) :
Page 4


  
s-BLOCK ELEMENTS & THEIR COMPOUNDS
Group 1 of the periodic table consists of the elements : lithium, sodium,
potassium, rubidium, caesium and francium .
The elements of Group 2 include beryllium, magnesium, calcium, strontium,
barium and radium.
Hydration Enthalpy :
The hydration enthalpies of alkali metal ions decrease with increase in
ionic sizes.Li
+
 has maximum degree of hydration and for this reasons
lithium salts are mostly hydrated e.g., LiCl . 2H
2
O
Physical properties :
All the alkali metal are silvery white, soft and light metals. Because of the
larger size, these element have low density. The melting and boiling point
of the alkali metals  are low indicating weak metallic bonding alkali metals
and their salts impart characteristic colour to an oxidizing flame.
Metal Li Na K Rb Cs
Colour Crimson
red
Yellow
Violet/
Lilac Red
violet
Blue
Chemical Properties:
The alkali metal are highly reactive due to their larger size and low ionization
enthalpy.
?   Reactivity towards air : They burn vigorously in oxygen forming
oxides. Lithium forms monoxide, sodium forms peroxide, the other metals
form superoxide.
?  Reducing nature: The alkali metals, are strong reducing agents,
lithium being the most and sodium the least powerful.
?  Solution in liquid ammonia: The alkali metals dissolve in liquid
ammonia giving deep blue solution which are conducting in nature.
M+ (x + y) NH
3
 ?? ? ?[M(NH
3
 )
x
 ]
+
 + [e(NH
3
)
y
]
?
The blue colour of the solution is due to the ammoniated electron and the
solutions is paramagnetic.
M
+
(am)
 
+ e
?
 + NH
3
 (?) ? ? ? ? ? ? ?
ding tan s on
 MNH
2
(am) + 1/2 H
2
(g)
In concentrated solution, the blue colour changes to bronze colour and
becomes, diamagnetic.
  
ANOMALOUS PROPERTIES OF LITHIUM
(i) exceptionally small size of its atom and ion, and (ii) high polarising
power (i.e., charge/ radius ratio ).
The similarity between lithium and magnesium is particularly striking and
arises because of their similar size: atomic radii, Li = 152 pm, Mg = 160
pm; ionic radii : Li
+
 = 76 pm, Mg
2+
 = 72 pm.
GROUP 2 ELEMENTS : ALKALINE EARTH METALS
The first element beryllium differs from the rest of the member and shows
diagonal relationship to aluminium.
Hydration Enthalpies
Hydration enthalpies of alkaline earth metal ions. Be
2+
 > Mg
2+
 > Ca
2+
 >
Sr
2+
 > Ba
2+
. The hydration enthalpies of alkaline earth metal ions are larger
than those of alkali metal ions.  Thus, compounds of alkaline earth metals
are more extensively hydrated than those of alkali metals , e.g., MgCl
2
and CaCl
2
 exist as MgCl
2 
.6H
2
O and CaCl
2
. 6H
2
O while NaCl and KCl do
not form such hydrates.
Physical Properties
The alkaline earth metals, in general, are silvery white, lustrous and relatively
soft but harder than the alkali metals. The melting and boiling point of
these metals are higher due to smaller sizes. Because of the low ionisation
enthalpies they are strongly electropositive in nature. The electrons in
beryllium and magnesium are too strongly bound to get excited by flame.
Hence these elements do not impart any colour to the flame.
Calcium, strontium and barium impart characteristic colour to the flame.
Metal Be Mg Ca Sr Ba
Colour No 
colour
No 
colour
Brick
red
Crimson Apple 
green
Chemical Properties
?  Reactivity towards air and water :  Beryllium and magnesium are
inert  to oxygen and water. Magnesium is more electropositive and burns
with dazzling brilliance in air to give MgO and Mg
3
N
2
 .Calcium, strontium
and barium are readily attacked by air to form the oxide and nitride.
,
?  Reducing nature : The alkaline earth metals are strong reducing
agent. This is indicated by large negative value of their reduction potentials.
,
  
?  Solution in liquid ammonia: The alkaline earth metals dissolve in
liquid ammonia to give deep blue black solution forming ammoniated ions.
M + (x + y) NH
3
 ? [ M(NH
3
)
x
]
2+ 
+ 2 [e(NH
3
)
Y
 ]
?
From these solutions, the ammoniates, [M(NH
3
)
6
]
2+
 can be recovered.
ANOMALOUS BEHAVIOUR OF BERYLLIUM
Beryllium the first member of the Group 2 metals, shows
anomalous behaviour as compared to magnesium and rest of the members.
Further, it shows diagonal relationship to aluminium.
Diagonal Relationship between Beryllium and Aluminium
The ionic radius of Be
2+
 is estimated to be 31 pm; the charge/
radius ratio is nearly the same as that of the Al
3+
 ion. Hence beryllium
resembles aluminium in some ways.
Compounds of s-block elements :
1. Sodium Oxide (Na
2
O) :
2. Sodium peroxide (Na
2
O
2
) :
  
3. Sodium Hydroxide (NaOH) :
4. Sodium Carbonate (Na
2
CO
3
) :
5. Quick Lime, Slaked Lime and Lime Water :
Page 5


  
s-BLOCK ELEMENTS & THEIR COMPOUNDS
Group 1 of the periodic table consists of the elements : lithium, sodium,
potassium, rubidium, caesium and francium .
The elements of Group 2 include beryllium, magnesium, calcium, strontium,
barium and radium.
Hydration Enthalpy :
The hydration enthalpies of alkali metal ions decrease with increase in
ionic sizes.Li
+
 has maximum degree of hydration and for this reasons
lithium salts are mostly hydrated e.g., LiCl . 2H
2
O
Physical properties :
All the alkali metal are silvery white, soft and light metals. Because of the
larger size, these element have low density. The melting and boiling point
of the alkali metals  are low indicating weak metallic bonding alkali metals
and their salts impart characteristic colour to an oxidizing flame.
Metal Li Na K Rb Cs
Colour Crimson
red
Yellow
Violet/
Lilac Red
violet
Blue
Chemical Properties:
The alkali metal are highly reactive due to their larger size and low ionization
enthalpy.
?   Reactivity towards air : They burn vigorously in oxygen forming
oxides. Lithium forms monoxide, sodium forms peroxide, the other metals
form superoxide.
?  Reducing nature: The alkali metals, are strong reducing agents,
lithium being the most and sodium the least powerful.
?  Solution in liquid ammonia: The alkali metals dissolve in liquid
ammonia giving deep blue solution which are conducting in nature.
M+ (x + y) NH
3
 ?? ? ?[M(NH
3
 )
x
 ]
+
 + [e(NH
3
)
y
]
?
The blue colour of the solution is due to the ammoniated electron and the
solutions is paramagnetic.
M
+
(am)
 
+ e
?
 + NH
3
 (?) ? ? ? ? ? ? ?
ding tan s on
 MNH
2
(am) + 1/2 H
2
(g)
In concentrated solution, the blue colour changes to bronze colour and
becomes, diamagnetic.
  
ANOMALOUS PROPERTIES OF LITHIUM
(i) exceptionally small size of its atom and ion, and (ii) high polarising
power (i.e., charge/ radius ratio ).
The similarity between lithium and magnesium is particularly striking and
arises because of their similar size: atomic radii, Li = 152 pm, Mg = 160
pm; ionic radii : Li
+
 = 76 pm, Mg
2+
 = 72 pm.
GROUP 2 ELEMENTS : ALKALINE EARTH METALS
The first element beryllium differs from the rest of the member and shows
diagonal relationship to aluminium.
Hydration Enthalpies
Hydration enthalpies of alkaline earth metal ions. Be
2+
 > Mg
2+
 > Ca
2+
 >
Sr
2+
 > Ba
2+
. The hydration enthalpies of alkaline earth metal ions are larger
than those of alkali metal ions.  Thus, compounds of alkaline earth metals
are more extensively hydrated than those of alkali metals , e.g., MgCl
2
and CaCl
2
 exist as MgCl
2 
.6H
2
O and CaCl
2
. 6H
2
O while NaCl and KCl do
not form such hydrates.
Physical Properties
The alkaline earth metals, in general, are silvery white, lustrous and relatively
soft but harder than the alkali metals. The melting and boiling point of
these metals are higher due to smaller sizes. Because of the low ionisation
enthalpies they are strongly electropositive in nature. The electrons in
beryllium and magnesium are too strongly bound to get excited by flame.
Hence these elements do not impart any colour to the flame.
Calcium, strontium and barium impart characteristic colour to the flame.
Metal Be Mg Ca Sr Ba
Colour No 
colour
No 
colour
Brick
red
Crimson Apple 
green
Chemical Properties
?  Reactivity towards air and water :  Beryllium and magnesium are
inert  to oxygen and water. Magnesium is more electropositive and burns
with dazzling brilliance in air to give MgO and Mg
3
N
2
 .Calcium, strontium
and barium are readily attacked by air to form the oxide and nitride.
,
?  Reducing nature : The alkaline earth metals are strong reducing
agent. This is indicated by large negative value of their reduction potentials.
,
  
?  Solution in liquid ammonia: The alkaline earth metals dissolve in
liquid ammonia to give deep blue black solution forming ammoniated ions.
M + (x + y) NH
3
 ? [ M(NH
3
)
x
]
2+ 
+ 2 [e(NH
3
)
Y
 ]
?
From these solutions, the ammoniates, [M(NH
3
)
6
]
2+
 can be recovered.
ANOMALOUS BEHAVIOUR OF BERYLLIUM
Beryllium the first member of the Group 2 metals, shows
anomalous behaviour as compared to magnesium and rest of the members.
Further, it shows diagonal relationship to aluminium.
Diagonal Relationship between Beryllium and Aluminium
The ionic radius of Be
2+
 is estimated to be 31 pm; the charge/
radius ratio is nearly the same as that of the Al
3+
 ion. Hence beryllium
resembles aluminium in some ways.
Compounds of s-block elements :
1. Sodium Oxide (Na
2
O) :
2. Sodium peroxide (Na
2
O
2
) :
  
3. Sodium Hydroxide (NaOH) :
4. Sodium Carbonate (Na
2
CO
3
) :
5. Quick Lime, Slaked Lime and Lime Water :
  
3Ca(OH)
2
 + 2Cl
2
 ?? ? Ca(OCl)
2
.Ca(OH)
2
.CaCl
2
.2H
2
O (bleaching powder).