Solid | Types of solid | Classification of solid

Solid is a state of matter which is a rigid, hard, three dimensional structure and has definite volume and definite shape and volume.

Types of solid

There are two types of solid.

Crystalline solid

The solid which has definite shape and atoms, ions or molecules are regularly arranged and particles have three dimensional arrangement is called Crystalline solid.

• Heat of fusion is specific in crystalline solid. 
• These are true solids.
• These solids have fixed and sharp melting points.

Amorphous solid

Amorphous means shapeless. Amorphous solids have indefinite shape and atoms, ions or molecules are regularly arranged and particles are in non repetitive arrangement.

• Heat of fusion is not fixed or not specific in amorphous solid.
• These are false solids.
• These solids have no sharp and fixed melting points.

Classification of solid

Ionic Solid

The crystalline solid in which positively charged and negatively charged ions are combined together by the electrostatic forces of attraction is called ionic solid.

Properties of ionic solid

•  These solids are crystalline solids in which cations and anions are arranged in different patterns.
• Under normal conditions of temperature and pressure, these solids never exist as liquid or gas.
• These solids are stable because they have an equal number of cations and anions.
• These solids are very hard because oppositely charged ions are closely packed and no space is present between them.
• These solids are less volatile.
• These solids show isomorphism and polymorphism.
• These solids do not conduct electricity in solid-state due to absence of free ions. But these solids are very good conductors of electricity in solution and molten form.
• These solids are soluble in water but not soluble in nonpolar solvents.
• When ionic compounds are soluble in water, these produce cations and anions.
• The rate of reactions of ionic compounds are much faster than the covalent compounds.
• These solids are brittle.

Covalent solid

The crystalline solid in which neutral atoms are held together by the covalent bonds is called Covalent bond.

These solids are also called atomic solids.

Types of covalent solid

There are two types of covalent solid.

Layered covalent solid

In which the atoms are joined together in two separate layers is called layered covalent solid.

Giant covalent solid

The solid in which atoms are joined together to form a big molecule is called gained covalent solid.

Properties of covalent solid

• These solids are crystalline solids in which atoms are arranged in a definite pattern.
• These solids have low volatility. 
• These solids are bad conductors of heat and electricity due to absence of free electrons.
• These salads are soluble only in nonpolar solvents such as benzene and ether. These solids are insoluble in polar solvents such as water.
• Rate of reactions of covalent solids are very slow as compared to ionic solids.