2. Atomic Structure

Mass: The amount of matter contained in a body.
Weight: The force in which a body is attracted towards center of gravity.
Classification of matter:-
1.Matter
2.Element
Matter:It is defined ad any particles which occupies mass & space.
Element:It is a simple substance which can't be divided into two or more substances
Eg: Metals,non metals
  • All metals are solid except mercury
  • All non metals are solid or gases except bromine
Chemical Symbol: It is abbreviated from an element.
Eg: Oxygen(O), Nitrogen (N)
Mixture: A mixture is a substance that contains two or more elements or compounds.
Eg: Air is a mixture of oxygen,Nitrogen and other gases.
  • Mixtures are of two types
  1. Homogeneous Mixture
  2. Heterogeneous Mixture
Homogeneous Mixture: This is a mixture has equal composition with its mass.
Eg: Sugar will be dissolved in water
Heterogeneous Mixture: A mixture having different composition throughout its mass.
Eg: Mixture of sand & cement
Compound:When two or more chemical elements combine then it form a compound.
Eg: H+O2---->H2O