What is Matter? | Science Class 5 PDF Download

Definition of Matter

Anything that occupies space and has mass is called matter. Matter can be solid, liquid or gas.

Matter is made up of tiny particles called molecules. A molecule cannot be seen with naked eyes. Molecules in different substances are arranged differently.

•  We can define molecule as the tiny unit of a substance that has all the properties of that substance. For example, an oxygen molecule has all the properties of oxygen gas. 
• Similarly, a water molecule will have all the properties of water. 
• Molecules can further be broken into atoms. They are called the building blocks of matter. 
• Atoms are the smallest unit of a matter and cannot be divided further. 

Elements and Compounds 

Atoms of the same kind combine to form elements. Scientists have discovered 118 elements so far on the earth. 

Atoms of different kinds combine to form compounds. Water is a common example of a compound which is made of two kinds of elements i.e. hydrogen and oxygen.

Arrangement of Molecules in Matter

There are three states of matter solid, liquid and gas. All the three states have different arrangement of molecules.

Solids

• In solids, the molecules are tightly packed. 
• They attract each other with a strong force of attraction.
• There is no intermolecular space between the molecules so they cannot move. 
• That is why solids have definite shape and volume.

Liquids

• In liquids, the molecules are not as closely packed as in solids. 
• The force of attraction between the molecules is less as compared to that of solids. 
• There is intermolecular space between the particles so that they can move freely. 
• That is why liquids can flow. 
• Liquids have definite volume but no definite shape. 

Gases

• In gases, the molecules are far apart with large intermolecular spaces between them. 
• They can move freely in all directions. 
• So, gases can flow easily and take up all the available space. 
• Gases do not have definite shape and volume.

Solids, Liquids and Gases in Water

• Some solids like salt and sugar are soluble in water. Their molecules spread themselves between the molecules of water. Some liquids like milk, glycerine and lemon juice also dissolve in water.

• The liquids that mix with each other are called miscible liquids.
• Liquids like oil and kerosene that do not dissolve in water are called immiscible liquids.
  
• Some gases like oxygen, carbon dioxide and nitrogen can dissolve in water. 
• Aquatic animals breathe in oxygen dissolved in water. 
• Aquatic plants take in carbon dioxide dissolved in water to make food. 
• In soft drinks, carbon dioxide is dissolved to make them fizzy. 
• When we boil water, small bubbles of air are seen on the inner side of the container. These bubbles are of dissolved gases that separate from water on heating.