What is Matter? Definition, Properties, Classification, States and Changes
Dear Friends! Matter is all around us. The air we breathe, the water we drink, the food we eat, the clothes we wear, the chair on which we sit, the book we read, the pen we write with, and the mobile or computer on which you are reading this science post are all made up of matter.
Even though we cannot see air, it is still matter because it has mass and occupies space. Matter is therefore one of the most basic concepts in chemistry.
In this science article, we will learn what matter is, its characteristics, classification, states of matter, physical and chemical properties, changes in matter and how matter is related to atoms and molecules. So, stay curious and read the complete article with full attention.
What is Matter?
Definition: Matter is anything that has mass and occupies space.
Lets understand in simple words, anything which has mass and takes up some space is called matter.
Examples of matter include:
- Water
- Air
- Soil
- Wood
- Iron
- Plastic
- Food
- Rocks
- Plants
- Mobile
- Laptop
- Computer
- Pendrive
- Books
- Pen
- Pencil
- Human body... etc.
Matter is made up of extremely small particles such as atoms, molecules and ions. These particles can be arranged and held together in different ways, giving substances their different properties.
For example, water is made up of water molecules. Each water molecule contains two hydrogen atoms and one oxygen atom and is represented by the formula H₂O.
Characteristics of Matter
Matter has some important characteristics.
1. Matter has mass
Every material object has mass. Mass is a measure of the amount of matter in an object.
The SI unit of mass is kilogram (kg).
2. Matter occupies space
Matter occupies a certain amount of space. The space occupied by a substance is called its volume.
The SI unit of volume is cubic metre (m³).
For liquids, litres and millilitres are also commonly used.
3. Matter is made up of particles
Matter is not continuous. It is made up of extremely small particles.
These particles may be atoms, molecules or ions depending on the substance.
4. Particles of matter are in continuous motion
The particles of matter are always moving. Their movement is different in solids, liquids and gases.
Heating generally increases the kinetic energy of particles and changes their motion. Increasing heat increases motion of particles, while decreasing heat decreases motion of particles.
5. There are spaces between particles
Particles of matter are separated by spaces. The amount of space between particles differs from one state of matter to another.
The spaces are very small in solids and much larger in gases.
Order of spaces in different types of mater- GAS > LIQUID > SOLID
6. Particles of matter attract one another
Particles exert attractive forces on one another. The strength and nature of these forces vary from substance to substance and from one state of matter to another states of matter.
Matter is Made up of Particles
A piece of matter may appear continuous to our eyes, but at the microscopic level it consists of very small particles.
For example, when sugar dissolves in water, the sugar does not simply disappear. Sugar molecules become distributed throughout the water.
Similarly, when the smell of perfume spreads across a room, perfume molecules move through the air.
The particle nature of matter helps us understand many everyday observations such as:
- Why gases can be compressed.
- Why liquids can flow.
- Why solids have a fixed shape.
- Why the smell of perfume spreads through a room.
- Why sugar dissolves in water.
- Why heating can change the state of a substance.
Classification of Matter
Matter can be broadly classified into:
Pure substances and Mixtures
A pure substance has a fixed composition and characteristic properties, whereas a mixture contains two or more substances physically combined together.
Pure Substances
Pure substances are classified into:
Elements and Compounds
Elements
An element is a pure substance consisting of only one type of atom.
Examples:
- Hydrogen (H)
- Oxygen (O)
- Carbon (C)
- Iron (Fe)
- Copper (Cu)
- Gold (Au)
An element cannot be broken down into simpler substances by ordinary chemical methods.
There are 118 known chemical elements in the modern periodic table. If you are curious to learn about all these 118 elements then read our science book "Interesting Facts About All Elements of Periodic Table", which is available on Amazon and Flipkart.
Compounds
A compound is a pure substance formed when atoms of two or more different elements combine chemically in definite proportions.
Examples:
A compound has properties different from those of the elements from which it is formed.
For example, sodium is a highly reactive metal and chlorine is a toxic gas, but when they combine chemically in the appropriate ratio, they form sodium chloride, commonly known as table salt that we enjoy in our food.
Mixtures
A mixture contains two or more substances which are physically combined.
The substances in a mixture are not chemically combined to form a new substance and can generally be separated by physical methods.
Examples of mixtures include:
- Air
- Soil
- Sea water
- Salt solution
- Brass
- mixture of oil and water
Unlike a compound, the components of a mixture do not have to be present in a fixed ratio.
For example, the amount of salt in a salt-water mixture can be changed without producing a new compound.
Types of Mixtures
Mixtures are mainly of two types:
- Homogeneous mixture
- Heterogeneous mixture
Homogeneous Mixture
A homogeneous mixture has a uniform composition throughout.
Examples:
- Salt solution
- Sugar solution
- Air
- Brass
A salt solution looks the same throughout because the dissolved salt is uniformly distributed in the water.
Heterogeneous Mixture
A heterogeneous mixture does not have a uniform composition throughout.
Examples:
- Mixture of sand and water
- Mixture of oil and water
- Soil
- Granite
Different components in these mixtures may be visible or can be separated using suitable physical methods.
States of Matter
The three common states of matter are:
- Solid
- Liquid
- Gas
Matter can also exist in other states under special conditions. Plasma and Bose-Einstein condensate (BEC) are two important examples.
The state of a substance depends mainly on factors such as temperature, pressure and the attractive forces between its particles.
Solid State
A solid has a fixed shape and fixed volume.
The particles in a solid are closely packed and are held together by attractive forces. They cannot move freely from one place to another but can vibrate about their mean positions.
Examples:
- Ice
- Wood
- Iron
- Copper
- Salt
- Diamond
Solids are generally difficult to compress because there is a very little empty space between their particles.
Liquid State
A liquid has a fixed volume but no fixed shape.
It takes the shape of the container in which it is kept.
The particles in a liquid are close to one another, but they can move past each other. Therefore, liquids can flow.
Examples:
- Water
- Milk
- Oil
- Alcohol
- Mercury
Liquids are much less compressible than gases because their particles are relatively close together.
Gaseous State
A gas has neither a fixed shape nor a fixed volume.
It takes the shape and volume of its container.
The particles of a gas are far apart and move rapidly in different directions. There are large spaces between the particles, which makes gases highly compressible.
Examples:
- Oxygen
- Hydrogen
- Nitrogen
- Carbon dioxide
- Water vapour
This is why gases can be compressed into a much smaller volume.
Comparison of Solid, Liquid and Gas
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Not fixed | Not fixed |
| Volume | Fixed | Fixed | Not fixed |
| Particle arrangement | Closely packed | Close together | Far apart |
| Particle movement | Mainly vibrational | Particles move past one another | Rapid and free movement |
| Compressibility | Very very low | Very low | High |
| Fluidity | No | Yes | Yes |
| Interparticle space | Very small | Moderate | Very large |
Factors Affecting the State of Matter
The state of a substance depends mainly on temperature, pressure and the forces of attraction between its particles.
Temperature
When a substance is heated, its particles generally gain kinetic energy and move more vigorously.
For example, heating ice provides energy to its particles and can change it into liquid water. Further heating can convert water into water vapour.
Pressure
Pressure is particularly important for gases.
Increasing pressure can bring gas particles closer together and, under suitable conditions, can help convert a gas into a liquid.
Interparticle Forces
Particles attract one another. Stronger attractive forces generally make it more difficult for particles to move apart.
This is one reason why different substances have different melting points and boiling points.
Change of State of Matter
Matter can change from one state to another when temperature or pressure is changed.
For example:
Ice → Water → Water vapour
Ice, liquid water and water vapour are all H₂O. The physical state changes, but the chemical identity of the substance remains the same.
The important changes of state are:
- Melting
- Freezing
- Vaporisation
- Condensation
- Sublimation
- Deposition
Melting
The conversion of a solid into a liquid on heating is called melting or fusion.
Solid → Liquid
For example:
Ice → Water
The melting point of pure ice at normal atmospheric pressure is 0°C.
Freezing
The conversion of a liquid into a solid on cooling is called freezing or solidification.
Liquid → Solid
For example:
Water → Ice
Pure water freezes at 0°C at normal atmospheric pressure.
Vaporisation
The conversion of a liquid into a gas is called vaporisation.
Liquid → Gas
Vaporisation can occur by evaporation or boiling.
Boiling
Boiling is the rapid vaporisation of a liquid throughout the liquid when its vapour pressure becomes equal to the external pressure.
At normal atmospheric pressure, water boils at 100°C.
The boiling point of a liquid changes when the external pressure changes.
For example, water boils at a lower temperature at high altitudes because atmospheric pressure is lower.
Evaporation
Evaporation is the slow conversion of a liquid into vapour from its surface.
It can occur at temperatures below the boiling point.
For example, wet clothes gradually become dry because water evaporates from their surface.
Evaporation also produces a cooling effect because relatively high-energy molecules escape from the surface of the liquid.
Condensation
The conversion of a gas or vapour into a liquid is called condensation.
Gas → Liquid
For example, water vapour in air can condense into water droplets when it comes in contact with a sufficiently cold surface.
This is why water droplets may appear on the outside of a glass containing a cold drink.
Sublimation
The direct conversion of a solid into a gas without passing through the liquid state is called sublimation.
Solid → Gas
Examples include:
- Naphthalene
- Camphor
- Dry ice (solid carbon dioxide)
Deposition
The direct conversion of a gas into a solid without passing through the liquid state is called deposition.
Gas → Solid
Thus:
Sublimation: Solid → Gas
Deposition: Gas → Solid
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Physical and Chemical Changes
Matter undergoes different types of changes. These changes can broadly be classified as:
- Physical changes
- Chemical changes
Physical Change
A physical change is a change in which the chemical identity of a substance remains unchanged.
Examples:
- Melting of ice
- Freezing of water
- Cutting of paper
- Breaking of glass
- Dissolving sugar in water
- Evaporation of water
For example, when ice melts, solid H₂O changes into liquid H₂O. No new substance is formed.
A physical change may be reversible or irreversible.
For example, melting of ice is reversible, whereas breaking a glass into pieces is practically irreversible.
Chemical Change
A chemical change is a change in which one or more new substances are formed.
Examples:
- Burning of wood
- Rusting of iron
- Digestion of food
- Cooking of food
- Making Tea or Coffee
- Reaction of an acid with a base
For example, iron reacts with oxygen and moisture over time to form rust. The composition and properties of the resulting material are different from those of iron.
The formation of new substances, rather than reversibility, is the important feature of a chemical change.
Difference Between Physical and Chemical Changes
| Physical Change | Chemical Change |
|---|---|
| No new substance is formed | One or more new substances are formed |
| Chemical composition remains unchanged | Chemical composition changes |
| May be reversible or irreversible | Involves chemical transformation |
| Example: melting of ice | Example: rusting of iron |
| Example: evaporation of water | Example: burning of wood |
Physical Properties of Matter
The properties which can be observed or measured without changing the chemical identity of a substance are called physical properties.
Important physical properties include:
- Colour
- Odour
- Density
- Melting point
- Boiling point
- Solubility
- Electrical conductivity
- Thermal conductivity
- Hardness
- Transparency
- State of matter
For example, we can measure the density of a substance without changing it into another substance.
Density
Density is the mass of a substance per unit volume.
It is represented by the formula:
Density = Mass / Volume
or
ρ = m/V
The SI unit of density is:
kg m⁻³
Another commonly used unit is:
g cm⁻³
Density is a useful physical property because different substances generally have different densities.
For example, under ordinary conditions, water has a density of approximately 1 g cm⁻³.
Chemical Properties of Matter
The properties which describe how a substance behaves during a chemical reaction are called chemical properties.
Examples include:
- Flammability
- Reactivity with oxygen
- Reactivity with acids
- Reactivity with bases
- Corrosiveness
- Ability to undergo oxidation or reduction
For example, the ability of iron to react with oxygen and moisture to form rust is a chemical property of iron.
Matter and Atoms
Matter is made up of atoms, molecules and ions.
An atom is the basic unit of an element that retains the chemical identity of that element.
An atom contains:
- Protons – positively charged particles
- Neutrons – electrically neutral particles
- Electrons – negatively charged particles
Protons and neutrons are present in the nucleus, while electrons occupy regions around the nucleus described by quantum mechanics.
Atoms can combine with one another to form molecules, ions and larger structures.
For example:
2H₂ + O₂ → 2H₂O
In this reaction, hydrogen and oxygen atoms are rearranged to form water molecules.
Molecules
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.
Examples include:
- H₂ – hydrogen molecule
- O₂ – oxygen molecule
- H₂O – water molecule
- CO₂ – carbon dioxide molecule
Not every substance consists of separate molecules. For example, sodium chloride forms an ionic lattice in its solid state, while diamond forms a giant covalent network.
This is why the arrangement of particles is important in determining the properties of matter.
Matter in Everyday Life
Almost everything we use in everyday life is made from matter.
Our clothes contain fibres. A steel spoon contains mainly iron along with other elements. Glass contains mainly silica along with other components. Plastic materials are made from polymers containing long chains of atoms.
Living organisms are also made of matter.
The human body contains water, proteins, carbohydrates, lipids, minerals and many other substances. Plants contain water, carbohydrates, proteins, cellulose and minerals.
Chemistry helps us understand the composition and behaviour of these substances.
Matter and Energy
Matter and energy are closely related.
In an ordinary chemical reaction, atoms are rearranged to form new substances. The atoms themselves are not destroyed or created in the chemical reaction.
For example:
Hydrogen + Oxygen → Water
The hydrogen and oxygen atoms are rearranged to form water molecules.
At a deeper level, We know the Einstein's famous equation:
E = mc²
shows that mass and energy are related.
This relationship becomes especially important in nuclear processes, where a very small change in mass can correspond to a very large amount of energy.
Therefore, the simple idea of conservation of matter is most directly applicable to ordinary chemical changes, while nuclear reactions require consideration of mass-energy equivalence.
Plasma – Another State of Matter
Plasma is commonly called the fourth state of matter.
Plasma is an ionised or partially ionised state of matter containing free electrons and ions. Its charged particles can show collective behaviour.
Examples of plasma include:
- The Sun and other stars
- Lightning
- Neon signs
- Some fluorescent lamps
- Plasma used in industrial processes
The Sun is therefore not an ordinary solid, liquid or gas. Most of the matter in the Sun exists in the plasma state.
Bose-Einstein Condensate
At extremely low temperatures, certain particles called bosons can occupy the same quantum state and behave collectively.
This unusual state is called a Bose-Einstein Condensate (BEC).
It was predicted from the work of Satyendra Nath Bose and Albert Einstein and was experimentally produced in dilute atomic gases in 1995.
BEC occurs under highly controlled laboratory conditions and is very different from the ordinary states of matter encountered in everyday life.
Matter in the Universe
Matter is not limited to the Earth.
The stars, planets, moons, galaxies and living organisms are all part of the Universe and contain ordinary matter.
However, ordinary matter makes up only a small part of the total mass-energy content of the Universe.
According to the standard cosmological model, approximately:
- 5% is ordinary matter
- 27% is dark matter
- 68% is dark energy
Dark Matter
Dark matter is a form of matter that does not appear to absorb, emit or reflect electromagnetic radiation significantly.
Therefore, it cannot be observed directly with ordinary telescopes.
Scientists infer its presence mainly from its gravitational effects on visible matter and the large-scale structure of the Universe.
Dark Energy
Dark energy is the name given to the unknown component associated with the accelerated expansion of the Universe.
Scientists are still studying its nature and origin.
These topics take us beyond ordinary chemistry into modern physics and cosmology, showing how our understanding of matter continues to develop.
Matter – From Everyday Objects to Atoms
A simple object such as a toothbrush may look completely different from a glass of water, a piece of iron or a leaf.
But all of them are made from matter.
If we look deeper, matter is made up of particles. These particles are built from atoms, and atoms can combine in different ways to produce an enormous variety of substances.
The arrangement and interactions of these particles determine whether a substance is hard or soft, solid liquid or liquid, electrically conductive or insulating, soluble or insoluble, reactive or unreactive.
This is one of the fascinating things about chemistry: a relatively small number of elements can combine in countless ways to produce the enormous variety of materials found around us.
Why is the Study of Matter Important?
The study of matter is the foundation of chemistry.
By studying matter, scientists can understand:
- Why substances have different properties.
- Why substances react with one another.
- How medicines work.
- How fuels produce energy.
- How plastics and polymers are made.
- How metals are extracted and used.
- How food is preserved.
- How batteries produce electricity.
- How new materials are developed.
- How pollutants affect the environment.
From a simple glass of water to a complex medicine, chemistry involves matter and the changes it undergoes.
Final Takeaway
Matter is everything around us that has mass and occupies space. It is made up of extremely small particles and can exist as elements, compounds or mixtures.
Matter commonly exists as solids, liquids and gases, while other states such as plasma and Bose-Einstein condensates occur under special conditions. Matter can also undergo physical changes such as melting and evaporation and chemical changes in which new substances are formed.
By studying the composition, structure, properties and behaviour of matter, chemistry helps us understand the materials that make up our everyday world.
Quick Revision – Matter
Matter: Anything that has mass and occupies space.
Mass: A measure of the amount of matter in an object.
Volume: The amount of space occupied by matter.
Element: A pure substance consisting of only one type of atom.
Compound: A pure substance formed when atoms of two or more different elements combine chemically in definite proportions.
Mixture: A physical combination of two or more substances.
Homogeneous mixture: A mixture having uniform composition throughout.
Heterogeneous mixture: A mixture that does not have uniform composition throughout.
Atom: The basic unit of an element that retains its chemical identity.
Molecule: An electrically neutral group of two or more atoms held together by chemical bonds.
Solid: State of matter having fixed shape and fixed volume.
Liquid: State of matter having fixed volume but no fixed shape.
Gas: State of matter having neither fixed shape nor fixed volume.
Plasma: An ionised or partially ionised state of matter containing free electrons and ions.
Density: Mass per unit volume of a substance.
Physical change: A change in which the chemical identity of a substance remains unchanged.
Chemical change: A change in which one or more new substances are formed.
Melting: Solid → Liquid
Freezing: Liquid → Solid
Vaporisation: Liquid → Gas
Condensation: Gas → Liquid
Sublimation: Solid → Gas
Deposition: Gas → Solid
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1. Interesting Facts About All Elements of Periodic Table
2. Science Adventures with Jag, Dils and Dad
