Why Are Particles of Matter Continuously Moving with Definition Examples and Applications
The physical world is made up of matter. Anything that has mass and takes up space is called matter. The matter is made up of particles with the same chemical nature as the matter itself. Particles of matter are sometimes called atoms or molecules; they are discrete particles, extremely small and invisible to the naked eye. But how small are the particles of matter? Matter particles have dimensions in the range of micrometre, nanometre, and picometer. Air, water, rock, iron, tree, wood, chicken everything are all examples of matter.
What are the Characteristics of Particles of Matter?
Every solid, liquid, and gas we see around us are matter composed of particles. The existence of matter in various states indicates interaction between particles. We see the ice melts and sugar dissolves in water. These phenomena are evidence of certain characteristics of matter particles:
Particles of matter always attract each other.
The matter has spaces between the particles.
There exists a force of attraction between particles that holds them together. This force of attraction is called cohesive force, and the property is referred to as cohesion. The cohesive force is strongest in the solids, and hence they have a distinct shape. The intermolecular separation is lowest in solids; thus, there is no space between the particles of a solid. The cohesive force gets weaker in liquid and subsequently weakest in gases. The particles of liquids and gases are relatively free and exhibit random motion.
Particles of matter have spaces in between them. Liquids and gas particles have a greater distance between them. When sugar dissolves in water, the sugar molecules occupy the spaces between water molecules, and hence we do not observe an increase in volume.
Motion of the Particles
Particles of matter are continuously moving; all particles exhibit motion above -273.15oC (known as the absolute zero temperature). The movement of particles is restricted in solids due to their rigid structure and high cohesive force. The particles in a solid vibrate but do not move from their place. The strength of the cohesion is demonstrated by the energy required to break solids.
A considerable force needs to be applied to break ice or stone. Chalk or pencil can be broken easier because the cohesive strength of ice or stone is more than that of chalk or pencil.
If the particle gains energy, it can overcome the attractive force, this is apparent in the case of ice which melts, absorbing heat from the surrounding. Particles in liquid and gas can vibrate freely and move from their position as these phases are less condensed, and the particles have higher energy than solid.
Diffusion and Brownian Motion of Particles of Matter
The movement of particles of matter is evident from phenomena such as Diffusion and Brownian motion. Let’s read them in detail below.
Diffusion
Diffusion is the phenomenon where particles of matter move from one region to another due to a concentration gradient; particles move from the region of higher concentration to a lower concentration.
When food is cooked, the aroma of the food spreads all across the house. This is due to diffusion; the food particle from the vessel during cooking diffuses to another corner of the house.
When a crystal of potassium permanganate is put in a beaker of water, the whole water turns purple without stirring. The crystal has permanganate particles in high concentration, which spreads throughout the beaker by diffusion.
Brownian Motion
Brownian motion is the phenomenon of random zig-zag motion of particles suspended in a medium. The phenomenon was first demonstrated by Robert Brown in 1827.
He suspended small pollen grains in water and observed that the pollen grains were moving rapidly in an irregular fashion throughout the water's surface. The phenomenon was explained by considering the motion of particles. The tiny water particles moved continuously and rapidly, hitting the pollens, which were themselves moving towards the surface of the water displaying an overall zigzag motion. This motion was named after Brown as the Brownian motion.
Interesting Facts
The gaseous phase and liquid phases are often referred to as condensed phases.
Below absolute zero, -273.15oC, all atomic movement and disorder disappear. This state cannot be physically reached.
The random movement of the particles contributes to the disorder of the system. This measure of the disorder of a system is termed entropy.
Key Features
All matter is made up of particles.
All particles above -273.15oC (absolute temperature) exhibit some kind of motion.
Solid matters display the lowest movement. The particles of solid show limited vibration.
Liquid and gases display motions such as diffusion and Brownian motion.
FAQs on Particles of Matter Are Continuously Moving in Kinetic Theory
1. What does it mean that particles of matter are continuously moving?
Particles of matter are continuously moving means that the atoms and molecules of any substance are always in motion due to their kinetic energy. This motion never stops, even in solids (except at absolute zero).
- In solids, particles vibrate about fixed positions.
- In liquids, particles slide past one another.
- In gases, particles move freely and rapidly in all directions.
2. What is the kinetic theory of matter?
The kinetic theory of matter states that all matter is made of tiny particles that are in constant random motion and possess kinetic energy. This theory explains the behavior of solids, liquids, and gases.
- Particles have spaces between them.
- Particles attract each other with intermolecular forces.
- Temperature is a measure of the average kinetic energy of particles.
3. How does temperature affect the movement of particles?
An increase in temperature increases the kinetic energy of particles, causing them to move faster. Conversely, lowering temperature reduces particle motion.
- In solids, particles vibrate more strongly at higher temperatures.
- In liquids, particles move more freely and evaporation increases.
- In gases, particles move faster, increasing pressure in a closed container.
4. What is diffusion in chemistry?
Diffusion is the spontaneous movement of particles from a region of higher concentration to a region of lower concentration due to their continuous motion. It occurs in gases, liquids, and even solids (very slowly).
- Example: The smell of perfume spreading in a room.
- In liquids: A drop of ink spreading in water.
5. Why do gases diffuse faster than liquids and solids?
Gases diffuse faster because their particles have higher kinetic energy and very weak intermolecular forces compared to liquids and solids. This allows gas particles to move freely over large distances.
- Large spaces between gas particles.
- Minimal attractive forces.
- High particle speed.
6. How does particle movement explain changes of state?
Changes of state occur because heating or cooling alters the kinetic energy of particles, affecting their motion and intermolecular forces. When particles gain energy, they move more freely.
- Melting: Solid → Liquid (particles overcome some attractive forces).
- Boiling: Liquid → Gas (particles escape completely).
- Freezing/Condensation: Energy decreases and motion slows.
7. What is Brownian motion and how does it prove particles are moving?
Brownian motion is the random zigzag movement of microscopic particles suspended in a fluid due to collisions with fast-moving molecules of the fluid. It provides experimental evidence for the continuous motion of particles.
- Observed by Robert Brown in 1827.
- Caused by unequal collisions of fluid molecules.
- More noticeable at higher temperatures.
8. Do particles in solids also move?
Yes, particles in solids continuously move by vibrating about their fixed positions. Although they cannot move freely like in liquids or gases, they still possess kinetic energy.
- Strong intermolecular forces hold particles in place.
- Vibrational motion increases with temperature.
- At absolute zero (0 K), theoretical motion stops.
9. How is gas pressure related to the continuous motion of particles?
Gas pressure is caused by the continuous collisions of fast-moving gas particles with the walls of a container. Each collision exerts a small force on the surface.
- More frequent collisions increase pressure.
- Higher temperature increases particle speed and pressure.
- Smaller volume increases collision frequency.
10. What is an example that shows particles of matter are continuously moving?
A common example of continuous particle motion is the spreading of a drop of ink in water without stirring. The ink particles mix uniformly due to their random motion.
- Perfume smell spreading in air.
- Sugar dissolving in water.
- Ammonia and hydrogen chloride gases forming white fumes of NH4Cl(s) when they diffuse and react.
