# Sorting Materials into Groups Notes

## Sorting or classification:

• The organization of the materials based on the properties and construction enables us to identify the similarities and differences between them. So, we can systematically arrange the materials.
• We can arrange the substances in the same group by identifying the similarities between the materials. While we can separate them on the basis of the differences between them.
• The substances can also be grouped by the similarity of the materials used to make them.

Table 1 shows the object and the materials used to make it.
Table 2 shows the material and the objects made by it.
Table 3 shows a single object made up of different types of materials.

## PROPERTIES OF MATERIALS

Appearance
Mostly the materials look different from each other. For example, metals look different from wood. They can be identified by the shine.
Lustre:
1. Some materials are lustrous(shiny) such as metals. While others are not shiny
2. The metals can lose their shine because of the presence of rust on them.

Hardness
The materials that can easily break are called soft materials like paper. Whereas, others cannot be crushed easily called hard materials like iron.
Transparency
1. Some substances that allow us to see pass through them are called transparent substances. The light can easily pass through them. The common examples of transparent objects are air, glass and some plastics
2. The objects that allow us to see but not clearly through them are called translucent objects. The examples of translucent objects are butter paper, tissue paper and thin plastic etc
3. The objects that do not allow us to see pass through them are called opaque objects. When the light falls on an opaque object, it does pass through it, meanwhile, it forms a shadow. Some examples of opaque objects are wood, human, stone and trees eSolubility in water
4. A solution is a mixture of homogeneous(same components) or heterogeneous(different components).
5. The material that is present in a small amount in a solution is called the solute. The solute can be dissolved or cannot be dissolved in a solution. For example, sugar can be dissolved in the water, but pieces of rock cannot.
6. The solute that can be dissolved in a solution is called soluble substances. While some other substances that are not dissolved in a solution called insoluble substances.
7. If the mixture of liquids successfully mix then it is called miscible liquids. While the liquids that do not mix with each other are called immiscible liquids.
8. Table 4 shows the solubility test of various materials in the water.

Texture
1. The feeling of roughness and smoothness while touching any object is called its texture.
2. The smooth objects have plane surfaces and no bumps or ridges. For example, flowers and baby’s skin etc(Figure 3: a).
3. The rough objects have bumps or ridges and irregular surfaces. For example, tree-bark
Conductivity

1. The substances that pass the electricity completely are called good conductors. For example, metals.
2. The substances that pass the electricity partially are called poor conductors. For example, graphite.
3. The substances that do not pass the electricity are called insulators. For example, wood.
Density and floatation
1. The mass per unit volume of a substance is called density.
2. The objects that have lower density than the water can float on it. For example, ice.
3. The objects that have higher density than the water sink to it. For example, metals.

Malleability
1. It is a property of substances that can be changed into thin sheets while beating up. For example, metals like gold and silver are beaten up into thin sheets with a hammer.

Ductility
1. It is a property of metals that allow them to change into wires. For example, the filament of an electric bulb is made up of tungsten metal.

## MATTER

Anything which occupies mass and space is called matter.
All the substances present in the universe are made up of matter.

Composition of matter
• Many atoms or a few atoms linked together to form matter.
• The smallest unit of a matter is called an atom.
• The same atoms linked together to form a molecule.
• The short description of  element and compound is given below:

STATES OF MATTER
The existence of a matter in different forms is known as states of matter.
There are three states of matter:-
a) Solid State
• The particles of the solid state substances are closely packed.
• The intermolecular force of attraction between the particles in very high.
• The particles are fixed at their places, only vibrate if they get higher energy.
• The solid state objects have definite shape and size.
• They also have definite volume.

b) Liquid State
• The particles of liquid have spaces between them.
• The intermolecular force of attraction is high but not as the particles of solid.
• The particles of liquid are continuously moving in random directions, and while moving, they collide with each other.
• The liquid substances take definite shape in a container.
• They have definite volume.

c) Gas State
• The particles of gaseous state are loosely packed.
• The intermolecluar force of attraction is very low.
• The particles can move freely in any direction.
• They do not have definite shape, size and volume.
• They can be compressed in a cylinder. For example, Liquid Petroleum Gas(LPG) and Compressed Natural Gas(CNG).

• Notes
• Assignments & NCERT Solutions

### Practice Question

Question 1 What is $\frac {1}{2} + \frac {3}{4}$ ?
A)$\frac {5}{4}$
B)$\frac {1}{4}$
C)$1$
D)$\frac {4}{5}$
Question 2 Pinhole camera produces an ?
A)An erect and small image
B)an Inverted and small image
C)An inverted and enlarged image
D)None of the above