Solid State
It is a state of matter which posses both definite shape and definite volume. In solids the particles are very close to each and tightly packed with a greater force of attraction.
Properties of Solids
1. Diffusibility
Diffusion also occurs in solids but its rate is very slow. If a polished piece of zinc is clamped with a piece of copper for a long time. After few years we will see that some particles of zinc are penetrated into copper and some particles of copper are penetrated into zinc. It shows that the diffusion in solids is possible but it occurs with a slow rate.
2. Compressibility
In solids the molecules are close to each other so it is not easy to compress a solid. In other words we can say that the effect of pressure on solids is negligible.
3. Sublimation
It is a property of some solids that on heating these solids are directly converted into vapours without liquification. This property of solids is known as sublimation.
4. Melting
When solids are heated, they are changed into liquids and the property is called melting of the solids.
5. Deformity
Solids may be deformed by high pressure. When a high pressure is applied on solids due to which some particles are dislocated the force of attraction is so strong that the rearranged atoms are held equally well with their new neighbours and hence the solid is deformed.
Classification of Solids
Solids are classified into two main classes.
1. Crystalline
2. Amorphous
1. Crystalline Solids
In a solid if the atoms are attached with each other with a definite arrangement and it also possesses a definite geometrical shape. This type of solid is called crystalline solid.
e.g. NaCl, NiSO4 are crystalline solids.
2. Amorphous Solids
In these solids there is no definite arrangement of the particles so they do not have a definite shape. The particles of such solids have a random three dimensional arrangement. Examples of amorphous solids are glass, rubber, plastic etc.
The properties of crystalline and amorphous solids are quite different from each other. These differences in properties are given below.
Difference of Geometry
1. Crystalline Solids
In crystalline solids particles are arranged in a definite order due to which it possesses a definite structure.
2. Amorphous Solids
In amorphous solids particles are present without any definite arrangement so they do not have definite shape.
Difference of Melting Point
1. Crystalline Solids
Crystalline solids have sharp melting point due to uniform arrangement.
2. Amorphous Solids
Amorphous solids melts over a wide range of temperature.
Cleavage and Cleavage Plane
1. Crystalline Solids
When a big crystal is broken down into smaller pieces the shape of the smaller crystals is identical with the bigger crystal. This property of crystalline solids is called cleavage and the plane from where a big crystal is broken is called cleavage plane.
2. Amorphous Solids
Amorphous solids do not break up into smaller pieces with an identical shape.
Anisotropy & Isotropy
1. Crystalline Solids
It is a property of crystalline solid that they show different physical properties in different direction. For example graphite can conduct electric current only through the plane which is parallel to its layers. This property is called anisotropy.
In amorphous solids the physical properties are same in all directions. This property of solids is called isotropy.
Symmetry in Structure
1. Crystalline solids are symmetric in their structure when they are rotated about an axis, their appearance remains same so they are symmetric in structure.
2. Amorphous Solids
Amorphous solids are not symmetric.
Types of Crystals
There are four types of crystals.
1. Atomic crystals
2. Ionic crystals
3. Covalent crystals
4. Molecular crystal
1. Atomic Crystals
Metals are composed of atoms. These atoms are combined with each other by metallic bond and the valency electrons in metals can move freely throughout the crystal lattice. This type of solid is called atomic crystal.
The properties of atomic crystals are
1. High melting point.
2. Electrical and thermal conductivity.
3. These are converted into sheets so these are malleable.
4. These are used as wire so these are ductile.
2. Ionic Crystals
Those solids which consists of negativity and positively charged ions held together by strong electrostatic force of attraction are called ionic crystals. Ionic crystalline solids possesses the following properties.
1. The melting and boiling point of ionic crystals is high.
2. They conduct electricity in molten state.
3. Ionic crystals are very hard.
4. Indefinite growth of crystals is also a property of ionic crystals.
3. Covalent Crystals
In covalent solids, the atoms or molecules are attached with each other by sharing of electrons. Such type of solids are called covalent solids e.g. diamond is a covalent solid in which carbon atoms are attached with each other by covalent bond. The other examples of covalent crystals are sulphur, graphite etc.
Covalent crystals possesses the following properties.
1. High melting point.
2. High refractive index.
3. Low density.
4. Molecular Crystals
Those solid in which molecules are held together due to intermolecular forces to form a crystal lattice are called molecular crystals e.g. iodine and solid CO2 are molecular crystals. The general properties of molecular crystals are as follows.
1. Low melting and boiling point.
2. Non – conductor of heat and electricity.
Isomorphism
When two different substance have same crystalline structure, they are said to be isomorphous and the phenomenon is called isomorphism.e.g. ZnSO4 and NiSO4 are two different substances but both are orthorhombic similarly the structure of CaCO3 and NaNO3 is frigonal.
Polymorphism
If a substance exist in more than one crystalline form it is called polymorphous and the phenomenon is known as polymorphism. E.g. sulphur exist in rhombic and monoclinic form similarly CaCO3 exist in trigonal and orthorhombic form.
Unit Cell
The basic structural unit of a crystalline solid which when repeated in three dimensions generates the crystal structure is called a unit cell.
A unit cell of any crystalline solid has a definite geometric shape and distinguish from other crystals on the basis of length of the edges and angle between the edges.
Crystal Lattice
In crystalline solids atoms, ions or molecules are arranged in a definite order and form a three dimensional array of particles which is known as crystal lattice
It is a state of matter which posses both definite shape and definite volume. In solids the particles are very close to each and tightly packed with a greater force of attraction.
Properties of Solids
1. Diffusibility
Diffusion also occurs in solids but its rate is very slow. If a polished piece of zinc is clamped with a piece of copper for a long time. After few years we will see that some particles of zinc are penetrated into copper and some particles of copper are penetrated into zinc. It shows that the diffusion in solids is possible but it occurs with a slow rate.
2. Compressibility
In solids the molecules are close to each other so it is not easy to compress a solid. In other words we can say that the effect of pressure on solids is negligible.
3. Sublimation
It is a property of some solids that on heating these solids are directly converted into vapours without liquification. This property of solids is known as sublimation.
4. Melting
When solids are heated, they are changed into liquids and the property is called melting of the solids.
5. Deformity
Solids may be deformed by high pressure. When a high pressure is applied on solids due to which some particles are dislocated the force of attraction is so strong that the rearranged atoms are held equally well with their new neighbours and hence the solid is deformed.
Classification of Solids
Solids are classified into two main classes.
1. Crystalline
2. Amorphous
1. Crystalline Solids
In a solid if the atoms are attached with each other with a definite arrangement and it also possesses a definite geometrical shape. This type of solid is called crystalline solid.
e.g. NaCl, NiSO4 are crystalline solids.
2. Amorphous Solids
In these solids there is no definite arrangement of the particles so they do not have a definite shape. The particles of such solids have a random three dimensional arrangement. Examples of amorphous solids are glass, rubber, plastic etc.
The properties of crystalline and amorphous solids are quite different from each other. These differences in properties are given below.
Difference of Geometry
1. Crystalline Solids
In crystalline solids particles are arranged in a definite order due to which it possesses a definite structure.
2. Amorphous Solids
In amorphous solids particles are present without any definite arrangement so they do not have definite shape.
Difference of Melting Point
1. Crystalline Solids
Crystalline solids have sharp melting point due to uniform arrangement.
2. Amorphous Solids
Amorphous solids melts over a wide range of temperature.
Cleavage and Cleavage Plane
1. Crystalline Solids
When a big crystal is broken down into smaller pieces the shape of the smaller crystals is identical with the bigger crystal. This property of crystalline solids is called cleavage and the plane from where a big crystal is broken is called cleavage plane.
2. Amorphous Solids
Amorphous solids do not break up into smaller pieces with an identical shape.
Anisotropy & Isotropy
1. Crystalline Solids
It is a property of crystalline solid that they show different physical properties in different direction. For example graphite can conduct electric current only through the plane which is parallel to its layers. This property is called anisotropy.
In amorphous solids the physical properties are same in all directions. This property of solids is called isotropy.
Symmetry in Structure
1. Crystalline solids are symmetric in their structure when they are rotated about an axis, their appearance remains same so they are symmetric in structure.
2. Amorphous Solids
Amorphous solids are not symmetric.
Types of Crystals
There are four types of crystals.
1. Atomic crystals
2. Ionic crystals
3. Covalent crystals
4. Molecular crystal
1. Atomic Crystals
Metals are composed of atoms. These atoms are combined with each other by metallic bond and the valency electrons in metals can move freely throughout the crystal lattice. This type of solid is called atomic crystal.
The properties of atomic crystals are
1. High melting point.
2. Electrical and thermal conductivity.
3. These are converted into sheets so these are malleable.
4. These are used as wire so these are ductile.
2. Ionic Crystals
Those solids which consists of negativity and positively charged ions held together by strong electrostatic force of attraction are called ionic crystals. Ionic crystalline solids possesses the following properties.
1. The melting and boiling point of ionic crystals is high.
2. They conduct electricity in molten state.
3. Ionic crystals are very hard.
4. Indefinite growth of crystals is also a property of ionic crystals.
3. Covalent Crystals
In covalent solids, the atoms or molecules are attached with each other by sharing of electrons. Such type of solids are called covalent solids e.g. diamond is a covalent solid in which carbon atoms are attached with each other by covalent bond. The other examples of covalent crystals are sulphur, graphite etc.
Covalent crystals possesses the following properties.
1. High melting point.
2. High refractive index.
3. Low density.
4. Molecular Crystals
Those solid in which molecules are held together due to intermolecular forces to form a crystal lattice are called molecular crystals e.g. iodine and solid CO2 are molecular crystals. The general properties of molecular crystals are as follows.
1. Low melting and boiling point.
2. Non – conductor of heat and electricity.
Isomorphism
When two different substance have same crystalline structure, they are said to be isomorphous and the phenomenon is called isomorphism.e.g. ZnSO4 and NiSO4 are two different substances but both are orthorhombic similarly the structure of CaCO3 and NaNO3 is frigonal.
Polymorphism
If a substance exist in more than one crystalline form it is called polymorphous and the phenomenon is known as polymorphism. E.g. sulphur exist in rhombic and monoclinic form similarly CaCO3 exist in trigonal and orthorhombic form.
Unit Cell
The basic structural unit of a crystalline solid which when repeated in three dimensions generates the crystal structure is called a unit cell.
A unit cell of any crystalline solid has a definite geometric shape and distinguish from other crystals on the basis of length of the edges and angle between the edges.
Crystal Lattice
In crystalline solids atoms, ions or molecules are arranged in a definite order and form a three dimensional array of particles which is known as crystal lattice
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