Forms of Matter
Concept: Solids, Liquids and Gases
A matter is anything that possesses volume and weight and occupies space.
- A matter has a definite mass.
- It can be soluble or insoluble in water.
- Different things are made using one or more forms of matter.
Atoms and molecules:
- Matter is made of very minute particles invisible to our eyes, called atoms.
- Atoms tend to move or vibrate.
- Two or more atoms strongly bond together and form bigger particles called molecules.
Forms of matter:
Matters are present in three main forms—
- Solids have a specific weight, mass and definite shape.
- These are visible and can be held.
- A solid has a definite shape because its molecules are strongly held together.
Example: Rubik’s cube, scale, helmet, etc.
- A liquid can flow freely but has a definite mass.
- The molecules of liquids are loosely held. Therefore, liquids are fluid in nature and can be poured.
- They take the shape of the container in which they are poured.
- Liquids do not have a fixed shape but have a fixed volume.
Example: Water, oil, petrol, diesel, etc.
- A gas does not have a specific shape and can flow freely in all directions.
- Gases feel lighter than solids and liquids as the molecules of gas are free to move in any direction.
- The atoms and molecules are not orderly arranged in gases.
- Gases do not have a fixed size, shape, or volume.
Example: Oxygen, carbon dioxide, hydrogen, helium.
Changes in the forms of matter:
- Solids, liquids and gases can interchange among themselves due to factors like temperature and pressure.
- The conversion of a liquid to a gas when heated is called evaporation.
Example: Change of liquid water to water vapour.
- The conversion of a gas to a liquid when cooled is called condensation.
- The conversion of a liquid to a solid is called solidification.
- The conversion of a solid to a liquid due to the application of heat is called melting.
Example: Formation of dew.
Example: Water changing into ice.
Example: Ice cubes changing into water
- The heat from the sunlight changes water from any water body into water vapour.
- The water vapour is lighter than the liquid water, due to which it moves in the upper layers of air.
- The air filled with water vapour reaches heights where the temperature is lower than the Earth’s surface, which condenses to form liquid water.
- The condensed water then falls on the Earth as rain, called precipitation.
Uses of matter:
- Uses of solids:
- Solid wax is used in candles, crayons, etc.
- Solid water, i.e., ice, is used to preserve the food items and in refreshing juices and drinks.
- The pen, paper, pencil, bat, ball, cupboard and many things around us are solids.
- Liquid water is used for drinking, cooking, washing, etc.
- Liquid fuels such as petrol and diesel need to run the vehicles.
- We use liquid oil in diyas.
- Cooking oil is an essential part of our diet.
- Oxygen helps in burning.
- Animals use oxygen to breathe, whereas plants use carbon dioxide to make food.
- The party balloons are filled with helium gas.
Mixtures of different forms:
- A combination of two or more substances of the same or different states is called a mixture.
- We often use mixtures of solids, liquids and gases.
Mass: The quantity of matter present in an object.
Soot: A black powdery substance produced from burning that settles on any surface.
Pressure: Measuring how much force is acting over an area.
Did You Know?
- The air we breathe is composed of gases like nitrogen, oxygen, carbon dioxide, water vapour, etc.
- The snow on the mountain can directly convert into water vapour without melting into liquid water first.
- Fire is nothing but a mixture of hot gases.