Elements and Compounds (Is Matter Around us Pure - 7) in HINDI for Class 9 NCERT Science

In this Science (Chemistry) video in Hindi for class 9 we explained elements and compounds. We defined them with examples and their properties. We also differentiate between elements and compounds. We also distinguished compounds with mixtures.

This topic is from 2nd chapter - "Is matter around us pure" from NCERT.

An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Elements can be normally divided into metals, non-metals and metalloids.

Metals usually show some or all of the following properties:
1) They have a lustre (shine).
2) They have silvery-grey or golden-yellow colour.
3) They conduct heat and electricity.
4) They are ductile (can be drawn into wires).
5) They are malleable (can be hammered into thin sheets).
6) They are sonorous (make a ringing sound when hit).

Examples of metals are iron, gold, silver, copper, sodium, potassium, mercury etc.

Non-metals usually show some or all of the following properties:
1) They display a variety of colours.
2) They are poor conductors of heat and electricity.
3) They are not lustrous.
4) They are not sonorous.
5) They are not malleable.

Examples of non-metals are hydrogen, oxygen, nitrogen, carbon (coal, coke), bromine, iodine, fluorine, chlorine etc.

Metalloids are elements having intermediate properties between those of metals and non-metals.

Some examples of metalloid are boron, silicon, germanium, arsenic, antimony, tellurium etc.

Some interesting facts of elements :-
• The number of elements known at present is 118.
• 92 elements are naturally occurring and the rest are manmade.
• Majority of the elements are solid.
• 11 elements are in gaseous state at room temperature. They are hydrogen, nitrogen, oxygen, flourine, chlorine, helium, neon, argon, krypton, xenon and redon.
• 2 elements are liquid at room temperature – mercury and bromine.
• Two elements, gallium and cesium become liquid at a temperature slightly above room temperature (30 degree C).

A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Some examples are water, carbon dioxide, methane, sodium chloride etc.

Difference between mixtures and compounds :-

1) Elements or compounds just mix together to form a mixture and no new compound is formed. Whereas, elements react to form new compounds.
2) A mixture has a variable composition. Whereas, the composition of each new substance (compound) is always fixed.
3) A mixture shows the properties of the constituent substances. But, the new compound has totally different properties.
4) The constituents of a mixture can be separated fairly easily by physical methods, like, evaporation, distillation, crystallisation etc. Whereas, the constituents of a compound can be separated only by chemical or electrochemical reactions.

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🔴 Click here to watch the whole playlist on Chapter 2 : 'Is Matter Around us Pure' for Class 9 :

https://www.youtube.com/watch?v=kbn4XVL8bqU&list=PL51pHkbQg-tcutvOax3QB62DSU59x-geY&index=2&t=0s

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Previous videos -

🔴 Is Matter Around us Pure ?
https://youtu.be/kbn4XVL8bqU

🔴 Solution
https://youtu.be/qBZZo9pexMw

🔴 Suspension
https://youtu.be/zSfdsCPt5xk

🔴 Colloidal Solution
https://youtu.be/JB_9ZbUoEFE

🔴 Separating the Components of a Mixture
https://youtu.be/6mNFNeUkHZI

🔴 Physical and Chemical Changes
https://youtu.be/FsXgaeIfWWI

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