- We are surrounded by matter. Matter is made of particles.
- Matter around us exists in three physical states viz. solid, liquid and gas. These physical states have their own characteristics.
- The forces of attraction between the particles are maximum in solids, intermediate in liquids and minimum in gases.
- The spaces in between the constituent particles are minimum in the case of solids, intermediate in liquids and maximum in gases.
- The states of matter are interconvertible. The state of matter can be changed by changing temperature and pressure.
- Matter can also be classified as pure and impure substances. Pure substances contain elements and / or compounds. Impure substances are called mixtures.
- Elements are basic substances which can not be broken down further.
- Compounds are made of elements. Compounds and mixtures have their own characteristic properties.
- Mixtures are of two types homogeneous and heterogeneous.
- Elements are represented by symbols. A symbol stands for one atom of the element and its atomic mass.
- Formula represents a molecule of an element or a compound. It stands for the molecular mass of the element or compound.
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