General characteristics of solid state Chemistry Notes
→ General characteristics of solid state are given below:
- Their mass, volume and shape are definite.
- Their intermolecular distances are short.
- They have strong intermolecular forces.
- The positions of their constituent particles (atoms, molecules or ions) are fixed and particles can oscillate about their mean positions only.
- The property of diffusion is more in gases and liquids as compared to solids.
- The flow of particles in solid state is not possible
- Their melting and boiling points are generally high
- Their thermal energy is low.
- The density of solids is more as compared to liquids and gases.
→ Note : Melting Point The temperature at which a solid and liquid phase may coexist in equilibrium, is called melting point as the temperature at which solid starts melting is called melting point. Boiling PointTM The temperature, at which the vapour pressure of a liquid becomes equal to atmospheric pressure, is called boiling point As we have studied that the distance between constituent particles of solids is very less.
→ So, intermolecular or inter ionic forces of attraction are strong in solid state. Now if the temperatue of substance is increase then there is an increase in thermal energy due to which inter molecular forces become weak. As a result, the constituent particles move away from each other.
→ At a sufficient distance, a substance is transformed from solid state to liquid state. On further increasing the thermal energy, the distance between constituent particles also increases and as a result, a substance gets converted into gaseous state.
→ ExampLe Water exists in solid state (ice) below 0°C, in liquid state (water) above 0°C and gaseous state (vapour) at 100°C.