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Particulate Nature of Matter - What Is Matter Composed of?

Grade 8CBSE

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

🔑Concepts

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Matter is anything that has mass and occupies space. According to the particulate nature, matter is made up of extremely small particles called atoms or molecules.

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Particles of matter have spaces between them, known as intermolecular space. The order of intermolecular space is: Gas>Liquid>SolidGas > Liquid > Solid.

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Particles of matter are continuously moving and possess kinetic energy. As temperature increases, the kinetic energy (K.E.K.E.) of the particles increases, causing them to move faster.

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Particles of matter attract each other with a force known as intermolecular force of attraction. This force is strongest in solids, intermediate in liquids, and weakest in gases: Fsolid>Fliquid>FgasF_{solid} > F_{liquid} > F_{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 an increase in temperature.

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The state of matter can be changed by altering temperature or pressure, which affects the distance and forces between the particles.

📐Formulae

Density=MassVolumeDensity = \frac{Mass}{Volume}

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

K.E.∝T (where T is temperature in Kelvin)K.E. \propto T \text{ (where T is temperature in Kelvin)}

💡Examples

Problem 1:

A block of iron has a mass of 1560 g1560\text{ g} and a volume of 200 cm3200\text{ cm}^3. Calculate the density of the iron block.

Solution:

Density=1560200=7.8 g/cm3Density = \frac{1560}{200} = 7.8\text{ g/cm}^3

Explanation:

Density is calculated by dividing the total mass (1560 g1560\text{ g}) by the total volume (200 cm3200\text{ cm}^3) occupied by the particles of the substance.

Problem 2:

Calculate the volume of a solid displaced in a measuring cylinder if the initial water level was 50 mL50\text{ mL} and the final level after immersing the solid is 85 mL85\text{ mL}.

Solution:

85−5035\begin{array}{r} 85 \\ - 50 \\ \hline 35 \end{array} Therefore, Volume=35 mL\text{Volume} = 35\text{ mL} or 35 cm335\text{ cm}^3.

Explanation:

The volume of the solid is the difference between the final volume and the initial volume of the liquid in the cylinder.

Problem 3:

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

Solution:

In hot water, particles have higher K.E.K.E.. Since K.E.=12mv2K.E. = \frac{1}{2}mv^2, a higher temperature leads to a higher velocity (vv) of particles, increasing the rate of diffusion.

Explanation:

Higher temperature increases the kinetic energy of both the water and ink particles, leading to more frequent collisions and faster intermixing.