STUDY MATERIAL FOR NDA CHEMISTRY
1. Chemical Reactions
Chemistry is that branch of science which concern with the composition of matter, its properties and structure. It also deals with the relation between changes in composition and changes in energy. The scope of the subject is vast as universe.
Branches of Chemistry
There are three main branches of chemistry
• Inorganic chemistry: It is the branch of chemistry dealing with all elements and their compounds. Compounds of carbon are not deal within this branch of chemistry.
• Organic chemistry: It is the branch of chemistry in which carbon compounds are studied.
• Physical chemistry: The laws and principles of chemical reaction are studied in this branch of chemistry.
Types of Changes
There are two types of changes mainly
1. Physical Changes
A physical change is a change in which the composition of a substance is not affected, i.e., no new substance is formed. e.g.,
• Some substances (in the form of crystals) can be obtained in pure state from their solutions by crystallisation. It is an example of a physical change.
• When an ordinary piece of iron is magnetised in the presence of a strong magnetising field. Here the colour, density, mass and the composition remains the same. Hence, this magnetisation is a physical change.
• The physical changes are reversible. e.g., the magnetisation can be reversed by ‘heating the piece of iron.
Some other important examples of physical changes are
Evaporation, distillation, sublimation, condensation etc.
Some facts about the physical changes are
(i) Physical changes are temporary and reversible.
(ii) Physical changes are due to the change in physical properties like colour, volume, state temporarily.
(iii) Composition of the constituent molecules remains same.
2. Chemical Changes
These changes results in the formation of new substances. In a chemical change, the composition and molecular structure of the substance undergoing changes are considered.
• When a piece of iron or nail is left in moist air for a long time it rusts and gives a reddish brown look. During rusting process iron combines with oxygen to give a new product. Here rusting, is a chemical change which cannot be reversed back.
2. Elements, Mixtures and Compounds
3. Laws of Chemical Combination
4. Atomic Structure
5. Oxidation and Reduction
6. Acids and Base
7. Chemistry of Non-metals [Hydrogen, Oxygen and Nitrogen]
8. Some Important Chemical Compounds
9. Carbon and Its Different Forms
11. Air and Water
12. Carbon Dioxide
13. Concept of Atomic, Molecular and Equivalent Masses
14. Chemical Bonding
15. Periodic Classification1.
1.Units, Measurements and Dimensions
2. General Properties of Matter
4. Dynamics & Laws of Motion
5. Work, Energy and Power
7. Gravitation .
8. Thermal properties of matter
9. Waves & sound
10. Electricity & Magnetism