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Particulate Nature of Matter - States of Matter and Interparticle Space

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Matter is composed of extremely small particles called atoms or molecules, which cannot be seen with the naked eye.

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Particles of matter have spaces between them called 'Interparticle Space' or 'Intermolecular Space'. This space is minimum in solids, moderate in liquids, and maximum in gases.

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Particles of matter are in continuous motion, possessing kinetic energy. The relationship between kinetic energy (K.E.K.E.) and temperature (TT) is given as K.E.∝TK.E. \propto T.

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Particles of matter attract each other with a force known as 'Interparticle Force of Attraction'. This force is strongest in solids (Solid>Liquid>GasSolid > Liquid > Gas).

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Diffusion is the spontaneous intermixing of particles of two different types of matter on their own. The rate of diffusion increases with temperature and is fastest in the gaseous state.

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In solids, particles are closely packed with a fixed arrangement, leading to a definite shape and volume. In liquids, particles are less closely packed, leading to a definite volume but no definite shape. In gases, particles are far apart, resulting in no definite shape or volume.

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Density is a characteristic property of matter defined as mass per unit volume: ρ=mV\rho = \frac{m}{V}.

📐Formulae

Density (ρ)=Mass (m)Volume (V)\text{Density } (\rho) = \frac{\text{Mass } (m)}{\text{Volume } (V)}

K.E.=12mv2K.E. = \frac{1}{2}mv^2

T(K)=T(∘C)+273.15T(K) = T(^{\circ}C) + 273.15

💡Examples

Problem 1:

Why does a drop of ink spread faster in hot water compared to cold water?

Solution:

The rate of diffusion increases with an increase in temperature.

Explanation:

According to the particulate nature of matter, particles possess kinetic energy (K.E.=12mv2K.E. = \frac{1}{2}mv^2). When the temperature of water (H2OH_2O) increases, the kinetic energy of the ink and water particles increases, causing them to move and intermix more rapidly.

Problem 2:

Calculate the density of a solid block that has a mass of 500 g500\text{ g} and a volume of 125 cm3125\text{ cm}^3.

Solution:

ρ=4 g/cm3\rho = 4\text{ g/cm}^3

Explanation:

Using the formula for density ρ=mV\rho = \frac{m}{V}, we substitute the given values: ρ=500 g125 cm3=4 g/cm3\rho = \frac{500\text{ g}}{125\text{ cm}^3} = 4\text{ g/cm}^3.

Problem 3:

A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

Solution:

This shows that particles of matter have spaces between them and the force of attraction is not insurmountable.

Explanation:

In liquids like H2OH_2O, the interparticle space is large enough and the interparticle forces of attraction are moderate (weaker than solids), allowing the diver to displace the particles and pass through.