MATTER:
1. In genkeral it exists in 3 states i.e., (i) Solid
(ii) liquid
(iii) gas.
2. Now-a-days there is a discussion on two more states of matter i.e., Plasma (Ionisedgases containing super energetic and super excited particles and Bose-Einsteincondensates or BEC (a gas at super low temperatures with extremely low density).
Boiling Point :
1.The temperature at which liquid converts in to vapours is called its boiling point.2. Boiling point of water is 100˚C.
3.The boiling point increases in the presence of impurities. That's why boiling point of sea water is more than the boiling point of pure water (as the former contains impurity).
4. It usually decreases at high altitudes,that's why at high altitudes, the boiling point of water is less than 100˚C and more time is required to cook a food.
Melting Point :
1. It is a temperature at which a substance converts from its solid state to liquid state. 2.Meling point of ice is 0˚C; It decrease in the presence of impurity
Atom, Molecule and Element
3. Atom is the smallest particle of a matter that takes part in chemical reactions, but cannot exist in free state.
4. Atom is made 43 of electrons, protons and neutrons.
5. Protons and neutrons reside in the nucleus (at the centre of atom) whereas electrons revolve around the nucleus.
6.Atoms combine to form molecules, the smallest part of matter which can exist in free state.
Isotopes and Isobars :
1. Isotopes have the same number of protons (i.e., atomic number), but different number of neutrons and mass number (atomic number + number of neutrons), e.g., 1H1, 1H2.2. Isobars have the same mass number but different atomic number.
Example: 18Ar40, 19K40.
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