Explain With The Help Of Activity That Particles Of Matter Are Continuously Moving
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Answer:
Atoms are incredibly small and cannot be seen with even the most powerful light microscope. We use multiple models of atoms to help explain chemical processes and describe their behaviour.
In gases the particles move rapidly in all directions, frequently colliding with each other and the side of the container. With an increase in temperature, the particles gain kinetic energy and move faster. The actual average speed of the particles depends on their mass as well as the temperature – heavier particles move more slowly than lighter ones at the same temperature. The oxygen and nitrogen molecules in air at normal room temperature are moving rapidly at between 300 to 400 metres per second. Unlike collisions between macroscopic objects, collisions between particles are perfectly elastic with no loss of kinetic energy. This is very different to most other collisions where some kinetic energy is transformed into other forms such as heat and sound. It is the perfectly elastic nature of the collisions that enables the gas particles to continue rebounding after each collision with no loss of speed. Particles are still subject to gravity and hit the bottom of a container with greater force than the top, thus giving gases weight. If the vertical motion of gas molecules did not slow under gravity, the atmosphere would have long since escaped from the Earth.
In liquids, particles are quite close together and move with random motion throughout the container. Particles move rapidly in all directions but collide with each other more frequently than in gases due to shorter distances between particles. With an increase in temperature, the particles move faster as they gain kinetic energy, resulting in increased collision rates and an increased rate of diffusion.
In a solid, the particles pack together as tightly as possible in a neat and ordered arrangement. The particles are held together too strongly to allow movement from place to place but the particles do vibrate about their position in the structure. With an increase in temperature, the particles gain kinetic energy and vibrate faster and more strongly.
The attractive force in solids need not be stronger than in liquids or gases. For example the forces between solid helium particles (at -270 degrees C) are still very weak. By comparison, the forces between iron vapour particles (requires very high temperatures) are very strong. If you compare different substances that are at the same temperature, then the average kinetic energy of the particles will be the same (i.e. if the particles have the same mass then they will move with the same speed), but the attractive forces in solids will be greater than those in liquids, which will be greater than those in gases. Attractive forces don't get weaker when a substance moves from the solid to the liquid to the gas state, rather the kinetic energy of the particles increases (implying faster motion), allowing them to overcome the attractive forces.
