is matter around us pure class 9 notes–Chapter 2

Ritik RajJuly 20, 2023July 24, 2023

is matter around us pure class 9 notes–Chapter 2: All Topic Covered which helps to improve your knowledge.

What is Mixture?

The material which consists of two or more pure substances percent in any proportion is called mixture.
It is of two types-

1. Homogeneous mixture:

It has same composition throughout.
beam of light will not scatter.
Example air, sugar mixed with water etc.
It is also known as solution.

2. Heterogeneous mixture:

It has different composition in different parts.
There are visible boundaries of separation between the components.
Example- mixture of sand and water, Mixture of soil and water, etc

What is a solution?

A solution is a homogeneous mixture of two or more substances, like lemonade, mixture of sugar and water, etc.

Solute- The component of the solution which is dissolved in the solvent is called solute. It is present in lesser quantity.

Solvent- The component of solution which dissolves the other component in it, is called the solvent. It is present in larger quantity

Ex- In the solution of sugar and water. Sugar is solute and water is solvent.

Properties of solution:

It is a homogeneous mixture
the solute particle in a solution can’t be seen with naked eyes.
The solute particle in a solution easily passes through filter paper.
Solution or transparent to light.

Concentration of solution:

It is the amount of solute present in the solution.
Solution can be dilute, concentrated, saturated, Unsaturated, depending on the amount of solute present in it.
Dilute solution- In a dilute solution, there is small amount of solute dissolved in the solution.
concentrated solution-. In concentrated solution there are large amount of solute dissolved in the solution.
Saturated solution- A solution in which no more solute can be dissolved at a given temperature is called saturated solution.
Unsaturated solution- A solution which contains solute less than the maximum amount of solute that can be dissolved at a given temperature is called the unsaturated solution.
Solubility- The amount of solute present in the saturated solution at a given temperature is called its solubility.

Suspension:-

A suspension is a heterogeneous mixture in which solute particles do not dissolve but remain suspended throughout the bulk of medium.
Here particles are visible to naked eye,
Ex- muddy water, etc.

Properties of suspension:

It is a heterogeneous mixture.
Particles can be seen by naked eyes.
Particles of suspension do not pass through the filter paper.
It is not transparent to light.

Colloidal solution:-

The Colloidal Solution appears to be homogeneous, but actually it is heterogeneous mixture. The particles of Colloidal are uniformly spread throughout the solution. Because of small size of colloid particle,0 we can’t see them with naked eyes.

Properties of colloid:

It is a heterogeneous mixture.
The particles of colloid can easily scatter a beam of visible light.
The size of particle is too small to be individually Seen by naked eye.

Types of pure substance

On the basis of their chemical composition, it is of two types, first one is elements and second one is compounds.

Elements:

In 1661. Robert Boyle was the first scientist to use the term element but the French chemist, Anthony Lavoisier (1743-1794) was the first to establish an experimentally useful definition of an element. He defined An element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
Generally, all the elements are solid.
Element can be divided into three groups, first one is metals, second one is non-metals and third one is metalloids.

Metals:-

They have luster (shine).
They have silvery grey or golden yellow color.
They easily conduct heat and electricity.
They are ductile which means it can be drawn into thin wires.
They are malleable i.e. it can be hammered into thin sheets.
They are sonorous. i.e. on hitting the metal, it makes a ringing sound.
Ex-. Gold, Silver, Iron, Potassium, Copper, Sodium etc.
Note- Mercury is the only metal which is liquid at room temperature.

Non metals-

They display a variety of colors.
They are poor conductors of heat and electricity.
They are not lustrous sonorous or malleable.
Ex- Hydrogen, Oxygen, Iodine, Carbon, Chlorine, Bromine, etc.

Note– Bromine is liquid at room temperature.

Metalloid:-

The element which have intermediate properties in between those of metals and non metals are known as metalloids.
Ex-boron, silicon, germanium etc.

Compounds:

It is a substance composed of two or more elements which are chemically combined with one another in a fixed proportion.

Mixture	Compounds
Here elements or compounds just mix together to form a new mixture, but no new compound is formed. It has a variable composition. It shows the properties of constituent substances. The constituent parti can be separated easily by physical method.	Here elements react with each other to form a new compound. The composition of each new substance is always fixed. The new substances which is formed has totally different properties. Here the constituents can only be separated by chemical or electromechanical reactions.