CBSE Class 8 Science Revision Notes Chapter 4

Class 8 Science Chapter 4 Notes

CBSE Class 8 Science Revision Notes Chapter 4 – Materials: Metals and Non-Metals

According to the modern periodic table, the elements are all generally divided into two classes, metals and non-metals.  Chapter 4 of Class 8 Science encapsulates this classification. This chapter will cover both the fundamental and more complex concepts of metals and non-metals. The physical and chemical characteristics of these elements are also discussed in detail.

Therefore, students must be attentive in class and clear their doubts to learn the chapter’s fundamental concepts. With the help of Class 8 Science Chapter 4 Notes, they can effectively revise the chapter and prepare for their exams easily. At Extramarks, subject matter experts prepare the Metals and Non-Metals Class 8 Science Notes Chapter 4 in a simple language that students find easy to understand and revise the sections explained in the chapter.

Extramarks notes will be a student’s last-minute revision guide providing all the necessary information in a nutshell, to revise the entire syllabus quickly and easily.

Revision Notes for CBSE Class 8 Science Chapter 4

Access Class 8 Science Chapter 4 – Materials: Metals and Non-Metals

Here are some of the key concepts  mentioned in the chapter:

Introduction

All of the objects in an environment are constructed from either metals or non-metals.

Metals are strong materials with specific distinguishing qualities that make them suitable for use in almost everything. Examples include zinc, copper, and iron.

They are used in making furniture, appliances, machines, buildings, and other everyday items.

Materials that lack these distinguishing characteristics are known as non-metals. Examples include oxygen, carbon, and sulphur.

Physical Properties of Metals

Metals have the ability to be hammered into thin sheets. This characteristic is referred to as “moldability.” Because of this, a substance can change shape and become thin sheets like foil or aluminium.

They also possess a quality known as ductility that enables them to be drawn into wires. This characteristic makes it possible to draw metals like copper into wires.

Metals are excellent heat conductors, which is why they are used to make heaters, irons, and other heating appliances.

Because metals are effective electricity conductors, materials like copper and aluminium are used to create electrical wires and cables.

Metals have an unusual ability to ring when they are struck forcefully. This is referred to as being ‘sonorous’. This characteristic is what causes a sound to be produced when something hits a metal surface.

Like gold and silver, some metals have a lustrous or shiny appearance.

Chemical Properties of Metals

Basic metal oxides are produced when the metals react with oxygen. When red litmus paper is added to an iron-based solution of rust, it turns blue, indicating the formation of a basic metal oxide.

Some metals react with water very quickly, like iron, while others react very slowly, like sodium, which is why it is kept in kerosene. Typically, when metals and water interact, metal hydroxides and hydrogen gas are produced.

Metal salts and hydrogen gas are created when metals and acids interact. A pop sound is produced if a match is held close to the mouth of a test tube containing magnesium ribbon and dilute hydrochloric acid. This is because hydrogen gas, which is produced in the reaction,  burns  as it approaches the matchstick.

Metal salts and hydrogen gas, which burn with a pop sound, are produced when some metals, including zinc and aluminium, react with bases like sodium hydroxide.

In their compounds and aqueous solutions, the metals frequently replace less reactive metals with more reactive metals. A red deposit can be seen at the bottom, as the blue colour of the copper sulphate and zinc aqueous solution vanishes. This is because as red copper is released, zinc, which is more reactive than copper, replaces it by forming zinc sulphate.

Uses of Metals

Metals are used to manufacture tools, machinery, cars, aeroplanes, nails, and other products due to their strength and durability.

Jewellery is made from metals like gold and silver because of their lustrous qualities.

Metals such as copper and aluminium are used to manufacture wires because they are ductile and efficient electrical conductors.

Mercury-containing metal is used in thermometers.

The steel and electroplating industries use metals like nickel and chromium.

Batteries are created using metals like lead.

Packaging materials are made from metals that can be rolled into sheets, such as aluminium.

Physical Properties of Nonmetals

Because they are fragile and crumble into powder when beaten, nonmetals are not malleable. Similar to how sulphur transforms into a powdery mass.

Except for carbon, none of the non-metals is ductile because they cannot be drawn into wires. Sports goods and musical instruments both use carbon fibre.

The only non-metal that is both a good conductor of heat and electricity is graphite.

Non-metallic materials have no sonority and produce no sound when struck. A wooden box doesn’t ring when it is struck.

Nonmetals are non-lustrous, which means they have a soft and dull appearance. For example, charcoal.

Chemical Properties of Nonmetals

In most cases, when non-metals and oxygen combine, acidic non-metallic oxides are created. For example, sulphur and oxygen combine to form sulphur dioxide gas. When this is dissolved in water, sulphurous acid is produced, which causes blue litmus paper to turn red, indicating the presence of acid.

Although they may be very reactive in air, nonmetals typically do not react with water. For example, phosphorus, which is highly reactive when exposed to airborne oxygen, is stored in water.

In general, any acid will react with non-metals.

Uses of Non-Metals

The most significant non-metal oxygen is necessary for survival, just as carbon is for plants.

In fertilisers, non-metals like nitrogen and phosphorus are frequently used.

Liquid hydrogen, a non-metal, is used to power rockets.

Non-metal graphite is used in pencils.

Easy Revision Techniques for Class 8 Science Chapter 4 Notes

Class 8 Science Chapter 4 Metals and Nonmetals Notes – Summary

Metal and nonmetals are explained in Chapter 4 of the Class 8 Science curriculum. The chapter covers what metals and nonmetals are with definitions and examples. By carefully reading the chapter and referring to the Class 8 Chapter 4 Science Notes, they can plan and cover the content of the chapter well in time. Appropriate illustrations are used to demonstrate the physical and chemical properties. In this chapter, students will delve a little further into what they studied in previous classes. Let us look at the content covered in Class 8 Chapter 4 Science Notes.

The introduction covers the physical and chemical properties of metals as well as their general applications. Students can learn how metals behave under various physical and chemical conditions by referring to these Chapter 4 Science Class 8 Notes.

In the next section, students will learn about the chemical and physical characteristics of nonmetals. They can compare the properties of metals and nonmetals to identify the differences between these two categories of elements. Students can also consult the Chapter 4 Science Class 8 Notes to help them understand the concepts.

Every concept is clearly explained in the Chapter 4 Science Class 8 Notes to aid in students’ understanding. They will understand the causes behind certain characteristics of metals. The parameters are the mass number and the number of valence electrons in the outermost shell of the element. Even though different metals share some common characteristics, there are some exceptions. To help students remember each of these exceptions, relevant examples are given in the Class 8 Notes for Metal and Nonmetal.

Understanding and remembering the chemical properties along with chemical equations can be made easier with Class 8 Science Chapter 4 Notes. Students can learn the equations and develop strategies to comprehend the properties of metals and non-metals.

Various reactions and their corresponding equations are explained in the Class 8 Science Chapter 4 Notes. Studying these reactions will help students define the chemical characteristics of metals and non-metals. For a better understanding of the reactions and their characteristics, they can refer to the Class 8 Science Chapter 4 Notes.

Why Use Extramarks Chapter 4 Science Class 8 Notes?

Using Materials Metals and Non-metals Class 8 Notes has several advantages, but their conceptual simplicity and clarity are the main benefits. To help every student finish the chapter revision in less time, subject matter experts have provided a succinct and to-the-point explanations of the concepts covered in the chapter.