CBSE Class-12 Chemistry Quick Revision Notes
Chapter-01: The Solid State
• Solid:
Solid is a state of matter in which the constituting particles are arranged very closely. The
constituent particles can be atoms, molecules or ions.
• Properties of solids:
a) They have definite mass, volume and shape.
b) They are incompressible and rigid.
c) Intermolecular distances are short and hence the intermolecular forces are strong.
d) Their constituent particles have fixed positions and can only oscillate about their
mean positions.
• Classification of on the basis of the arrangement of constituent particles:
a) Crystalline solids: The arrangement of constituent particles is a regular orderly
arrangement. Example: iron, copper, diamond, graphite etc.
b) Amorphous solids: The arrangement of constituent particles is an irregular
arrangement. Example: Glass, plastics, rubber etc.
• Properties of crystalline solids:
c) They have a definite characteristic geometrical shape.
d) They have a long range order.
e) They have a sharp melting point.
f) They are anisotropic in nature i.e. their physical properties show different values
when measured along different directions in the same crystal.
g) They have a definite and characteristic heat of fusion.
h) They are called true solids.
i) When cut with a sharp edged tool, they split into two pieces and the newly generated
surfaces are plain and smooth.
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, • Polymorphic forms or polymorphs:
The different crystalline forms of a substance are known as polymorphic forms or
polymorphs. For example: graphite and diamond.
• Characteristics of amorphous solids:
a) They have an irregular shape.
b) They have a short range order.
c) They gradually soften over a range of temperature.
d) They are isotropic in nature i.e. their physical properties are the same in all
directions.
e) When cut with a sharp edged tool, they cut into two pieces with irregular surfaces.
f) They do not have definite heat of fusion.
g) They are called pseudo solids or super cooled liquids. This is because they have a
tendency to flow, though very slowly.
Types of crystalline solids:
A. Molecular Solids
Constituent Particles: Molecules
Type of Constituent Bonding/ Electrical Physical Melting Examples
Solid Particles Attractive conductivity nature point
Forces
Non-polar Molecules Dispersion or Insulator Soft Very Ar, CCl4,
solids London forces low H2, I2,
CO2
Polar Molecules Dipole- dipole Insulator Soft Low HCl, solid
solids interactions , solid NH3
Hydrogen Molecules Hydrogen Insulator Hard Low H2O (ice)
bonded bonding
B. Ionic Solids
Constituent Particles: Ions
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Chapter-01: The Solid State
• Solid:
Solid is a state of matter in which the constituting particles are arranged very closely. The
constituent particles can be atoms, molecules or ions.
• Properties of solids:
a) They have definite mass, volume and shape.
b) They are incompressible and rigid.
c) Intermolecular distances are short and hence the intermolecular forces are strong.
d) Their constituent particles have fixed positions and can only oscillate about their
mean positions.
• Classification of on the basis of the arrangement of constituent particles:
a) Crystalline solids: The arrangement of constituent particles is a regular orderly
arrangement. Example: iron, copper, diamond, graphite etc.
b) Amorphous solids: The arrangement of constituent particles is an irregular
arrangement. Example: Glass, plastics, rubber etc.
• Properties of crystalline solids:
c) They have a definite characteristic geometrical shape.
d) They have a long range order.
e) They have a sharp melting point.
f) They are anisotropic in nature i.e. their physical properties show different values
when measured along different directions in the same crystal.
g) They have a definite and characteristic heat of fusion.
h) They are called true solids.
i) When cut with a sharp edged tool, they split into two pieces and the newly generated
surfaces are plain and smooth.
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, • Polymorphic forms or polymorphs:
The different crystalline forms of a substance are known as polymorphic forms or
polymorphs. For example: graphite and diamond.
• Characteristics of amorphous solids:
a) They have an irregular shape.
b) They have a short range order.
c) They gradually soften over a range of temperature.
d) They are isotropic in nature i.e. their physical properties are the same in all
directions.
e) When cut with a sharp edged tool, they cut into two pieces with irregular surfaces.
f) They do not have definite heat of fusion.
g) They are called pseudo solids or super cooled liquids. This is because they have a
tendency to flow, though very slowly.
Types of crystalline solids:
A. Molecular Solids
Constituent Particles: Molecules
Type of Constituent Bonding/ Electrical Physical Melting Examples
Solid Particles Attractive conductivity nature point
Forces
Non-polar Molecules Dispersion or Insulator Soft Very Ar, CCl4,
solids London forces low H2, I2,
CO2
Polar Molecules Dipole- dipole Insulator Soft Low HCl, solid
solids interactions , solid NH3
Hydrogen Molecules Hydrogen Insulator Hard Low H2O (ice)
bonded bonding
B. Ionic Solids
Constituent Particles: Ions
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