Particles of Matter: An Introduction
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 Motion of Particles
1. How is the motion of particles and temperature related?
The motion of a particle has kinetic energy; temperature is the measure of this kinetic energy. The fast movement of particles is related to high temperature.
2. What is thermal motion?
Thermal motion is the random motion exhibited by all the particles above absolute zero. Thermal motion is the motion due to heat energy, so the higher the temperature higher is the thermal motion. Particles of solids have the least thermal motion, followed by liquids and gases.
3. What are subatomic particles?
Particles of matter are often discrete atoms, which are composed of subatomic particles. Subatomic particles are protons, neutrons and electrons. Thus, every atom is composed of protons, neutrons and electrons.
