SOME BASIC CONCEPT OF CHEMISTRY

 

SOME IMPORTANT TERMS:-

1) ATOM: -The smallest particle of an matter, which may or may not have an independent existence but always takes place in a chemical   reaction is called an atom.

2) MOLECULES: - A molecule is defined as the smallest unit of a compound that contains the chemical properties of the compound. Molecules are made up of groups of atom.

 

3) MATTER:- Anything that has mass and occupies space is called matter. A matter is made up of tiny particles. These particles are invisible to the naked eye.

 

4) MIXTURE:- .Mixtures are formed when two or more substances (elements or compounds) mix together without participating in a chemical change. The substances need not necessarily mix in a definite ratio to form a mixture.

 

 

a) HOMOGENEOUS MIXTURE - A mixtures in which the components mixed are uniformly distributed throughout the mixture.. Key points regarding such mixtures are:

• Particles are distributed uniformly
• We can’t judge a homogeneous mixture by just seeing it
• Homogeneous mixtures are also called solutions
• Uniform composition
• Example: Sweet water, vinegar, etc.

 

    b) HETEROGENEOUS - A mixture in which all the components are completely          mixed and all the particles can be seen under a microscope. Key points regarding this type of mixture:

• Particles are distributed non uniformly
• We can judge a heterogeneous mixture by just seeing it
• Non-uniform composition
• Example: seawater, sand & water, etc.

 

5) PURE SUBSTANCES - Pure substances are substances that are made up of only one kind of particles and has a fixed or constant structure. Ex- Gold, Silver & etc.

 

 

      a) ELEMENTS - It cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. Ex- H2, Na & etc.

 

    b) COMPOUNDS - They are chemical substances made up of two or more elements that are chemically bound together in a fixed ratio. Ex- NaCl, H2O & etc

 

6) MASS – The amount of matter present in the substance is called mass. It is constant quantity.

 

7) WEIGHT - The weight of an object is the force acting on the object due to gravity. It is vary place to place.

                                                 W = mg

W = Weight of an object

m = mass of an object

g = acceleration due to gravity

In SI base units: kg⋅m⋅s⁻²

 

SI unit: newton (N)

 

8) DENSITY:-It is define as the closeness of particles or we can say that it is the ratio of mass & volume of the object.

                                    DENSITY = MASS/VOLUME

SI UNIT – Kg m^-3

9) TEMPERATURE - Temperature is a physical quantity that expresses hot and cold. There are three common way to measure temperature – a) Degree Celsius (C)         b) Degree Fahrenheit (F)       c) kelvin (K)