Classification ofMatter We can classify the matter by its state.
Solids have a set volume and shape. The inter molecular force of attraction for solid matter is very strong.
Liquids have a set volume, but change shape. The inter molecular force of attraction for liquid matter is weaker than solid matter.
Gases have neither definite volume nor shape. The inter molecular force of attraction for gaseous matter is negligible.
Plasma which are usually gaseous state of matter in which a part or all of the atoms or molecules are dissociated to form ions.
We can also classify the matter by its chemical composition.
An elementis a pure substance made up of atoms with the same number of protons. As of 2011, 118 elements have been observed, 92 of which occur naturally. Carbon (C), Oxygen (O), Hydrogen (H) are the examples of the elements.
The periodic tableis a tabular representation of the known elements.
A compoundconsists of two or more chemical elements that are chemically bonded together. Water (H2O) and table sugar (C12H22O11) are examples of chemical compounds. The ratio of the elements in a compound is always the same. For example in water, the number of H atoms is always twice the number of O atoms.
A mixtureconsists of two or more substances (element or compound) mixed together without any chemical bond. Salad is a good example. We can separate the mixture into its individual components by mechanical means.
Ex.2 Answer the questions. 1. Can we classify the matter by its state?
2. What states of matter do you know?
3. Describe solids, liquids, gas and plasma.
4. What are the examples of the elements?
5. How many elements does the compound consist of?
