Sorting Materials into Groups: We came across a large number of objects on a daily basis. We have seen that some of them are living things, and some are non-living things. They aren’t all the same form, size, colour, or application. We employ each of them in accordance with our requirements and in light of their characteristics. In this way, we are grouping or sorting the things connected to each other. In this article, we are going to discuss the sorting of materials and the different properties of materials in detail.

Need for Classification

Grouping similar things according to some basis or criteria is called classification. We can keep dissimilar objects away by the method of classification. Therefore, classification is very important in our lives. It helps us to locate things easily. Classification is very useful for scientists to study different materials and their properties systematically.

Materials and their Classification

A substance or a thing that is used to make different objects is called material. Materials can be classified on the basis of their properties. For example, matter (Any material that has mass and occupies space) is classified into three based on the arrangement of particles in them. The three states are Solid, Liquid and Gaseous state. They can be explained in the following manner:

States of Matter

1. Solid State: This form of matter has a definite shape and volume. In solid state, the particles are arranged very closely. Examples of solids include paper, glass, wood, steel, etc.

2. Liquid State: Liquids have a definite volume, but they do not have a definite shape. The particles in a liquid are somewhat loosely packed compared to solids. Examples of liquids include water, milk, paint, oil, etc.

3. Gaseous State: This state of matter has neither definite shape nor fixed volume. The particles in this state of matter are very loosely packed. Examples of gases include oxygen, hydrogen, carbon dioxide, etc.

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Water is a form of matter which can exist in all three states naturally. That is ice (solid), water (liquid) and water vapour (gas).

Now we have understood that the property used for the above classification is the arrangement of particles. Apart from this, materials will have different properties that we can use to classify them. Let us learn the different properties of materials in detail.

Properties of Materials

Different materials will have different properties. These properties of a material are very important in using it to make a particular object. A material that is suitable for one product may not be suitable for another. For example, buckets, jugs, toys, chairs can be made out of plastic but not cooking utensils, because plastic will melt on heating. Now, let us study some of the important properties of materials.

1. Colour, Odour and Taste

Colour is one of the most differentiating properties of a material. For example, we can differentiate the turmeric powder (yellow colour) and chilli powder (red colour) by just looking at them. Similarly, various types of perfumes are identified by their distinctive smell. We used to classify the edible items as sweet, salty, spicy, sour, etc. by tasting them. Therefore, we can say that colour, taste and odour are some distinctive properties of materials.

2. Appearance

Generally, materials look different from one another. For example, iron looks different from paper. A steel almirah, an aluminium foil, and a brass vase shine more than a wooden chair. Gold jewellery shines but the paper of your notebook does not. This shine is called lustre. Materials that shine or have lustre are generally metals and these materials are called lustrous materials. Some of them include iron, copper, silver and gold. Apart from metals, some non-metals will also show lustre. For example, iodine crystals and graphite are lustrous in nature.

Some materials like wood, paper and stone do not have lustre. These are called non-lustrous materials.

Have you seen some metals when exposed to air loses their shine and give a dull appearance? This is due to the action of air and moisture on the metal (this process is called corrosion or rusting). This dullness can be removed by rubbing their surfaces with sandpaper.

3. Hardness

On the basis of hardness also, we can classify materials. Different materials will have different degrees of hardness. The materials that compress easily are said to be soft and those which are difficult to compress are said to be hard in nature. For example, stone and steel are hard whereas cotton and sponge are soft in nature.

4. Solubility in Water

Let us discuss the solubility of different substances in water. 

Solubility of Solids in Water

We know that water is an important liquid. As it can dissolve many substances, it is known as the universal solvent. The property of a material to dissolve in a liquid is called its solubility. Such a type of substance is generally known as a soluble substance. For example, common salt dissolves in water. Therefore, it is a soluble substance.

When chalk powder is added to water, it will not dissolve in it. This is because it is an insoluble substance. 

Solubility of Liquids in Water

Apart from solids, liquids also will dissolve in water. Those liquids mixed with each other is called miscible liquids. For example, lemon juice and water are miscible liquids. Also, vinegar and water are miscible liquids. 

Certain liquids will not mix with each other. They are called immiscible liquids. For example, coconut oil will not get dissolved in water. Therefore, they are immiscible liquids. 

Solubility of Gases in Water

Some gases like oxygen, carbon dioxide, etc. also will dissolve in water. Plants and animals living in water use these gases for their survival. Gases such as nitrogen and hydrogen are almost insoluble in water. 

5. Density: Floating and Sinking of Substances

When we add sawdust and cork to water, they float on it. Similarly, when we add stone and washing powder into water, they will sink in water. Why is it so? This can be explained on the basis of the density of substances. 

The mass per unit volume of a substance is known as its density. Substances that are less dense than water will float on it whereas the substances which are denser than water will sink on it. 

6. Transparency

Based on transparency, materials can be classified into three: Transparent, translucent, and opaque.

Transparent Materials: The materials that allow light to pass through them are called as transparent materials. We can see objects clearly through a transparent material. Glass is an example of a transparent material.

Translucent Materials: The materials that allow light to pass through them partially are called as translucent objects. We can see objects partially through a translucent material. Butter paper is an example of a translucent material.

Opaque Materials: Opaque materials will not allow light to pass through them. We cannot see objects through an opaque material. For example, wood is an example of an opaque material. 

Important Questions on Sorting of Materials into Groups

Q.1. What are the advantages of the classification of materials?
Ans: The classification of materials helps us to locate things easily and conveniently. Classification is very useful for scientists to study different materials and their properties systematically. These are the main advantages of the classification of materials.

Q.2. How is matter classified?
Ans: Matter is classified into three states on the basis of the arrangement of particles in it. The three states are solids, liquids, and gases.

Q.3. Write any four properties of materials.
Ans: Different materials have different properties. Four of them include:
(i) Appearance
(ii) Density 
(iii) Transparency
(iv) Solubility 

Summary

We are now familiar with the concept of classification or sorting of materials. Classification of materials is important as it helps to make things easier while using them. From the article, it is also clear that materials can be grouped on the basis of different properties like appearance, solubility, density, transparency, etc. The knowledge about the properties of materials and grouping them accordingly makes learning easier. Overall, we can say that the logic of grouping applies to all walks of life. 

FAQs

Q.1. What is sorting?
Ans: Grouping similar things according to some basis or criteria is called sorting. It is also known as classification.

Q.2. Why do we need to sort materials into groups?
Ans: Sorting materials help us to locate things easily. The logic of grouping applies in all walks of life.

Q.3. How does sorting materials into groups help us give any reason?
Ans: Sorting materials into groups help us in many ways. For example, it helps us to locate things easily. Classification is very useful for scientists to study different materials and their properties systematically.

Q.4. How do we group the materials?
Ans: We group different materials according to their properties. These properties include appearance, transparency, solubility, lustre, etc.

Q.5. What is the basis of sorting materials?
Ans: Materials are generally classified on the basis of the similarities or differences in their properties.

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