Class 7 Science - KARNATAKA
The World of Metals and Non-metals
In the chapter 'The World of Metals and Non-metals', Karnataka (KSEEB) Class 7 students explore the fascinating physical and chemical properties that divide all elements into two main groups. You will learn why metals shine, conduct electricity, and make ringing sounds, while non-metals are usually dull, brittle, and poor conductors. The chapter also covers how they react with oxygen, water, and acids to form different compounds. Understanding this division is crucial for your board exams as it forms the foundation for advanced chemistry in higher classes, frequently appearing in objective questions and descriptive tests.
Start Learning FreeKey Concepts
Physical Properties of Metals
Metals are generally hard, lustrous (shiny), malleable (can be beaten into sheets), ductile (can be drawn into wires), and are good conductors of heat and electricity.
Physical Properties of Non-metals
Non-metals are mostly soft, dull in appearance, non-malleable, non-ductile, and poor conductors of heat and electricity, existing as solids, liquids, or gases.
Reaction with Oxygen
When metals react with oxygen, they form basic oxides that turn red litmus blue. Non-metals react with oxygen to form acidic or neutral oxides that turn blue litmus red.
Reaction with Acids
Most metals react with dilute acids to produce metal salts and hydrogen gas, which burns with a pop sound. Non-metals generally do not react with dilute acids.
Displacement Reactions
A more reactive metal displaces a less reactive metal from its salt solution in water, demonstrating the varying reactivity of different metals.
Important Formulas
Board Exam Info
This chapter typically carries around 5 to 8 marks in the Karnataka (KSEEB) Science examinations. Common question types include defining properties like malleability and ductility, giving reasons why certain materials are used for specific purposes (e.g., electrical wires), and identifying the products formed during chemical reactions.
Frequently Asked Questions
Why are copper and aluminium used for making electrical wires?
Which liquid metal is used in thermometers?
How can we test the gas produced when a metal reacts with an acid?
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