Class 7 Science - RAJASTHAN
The World of Metals and Non-metals
In this chapter, Rajasthan Board Class 7 students explore the fascinating world of materials by dividing them into two main groups: metals and non-metals. You will learn about their distinct physical properties like malleability, ductility, conduction of heat and electricity, and sonority. The chapter also covers their chemical behaviors, such as how they react with oxygen, water, and acids. Understanding these differences helps us choose the right materials for everyday tools, electrical wires, and cooking utensils. Scoring well in this chapter is important as it builds the foundational chemistry concepts tested in board exams.
Start Learning FreeKey Concepts
Physical Properties of Metals
Metals are generally hard, shiny, malleable, ductile, good conductors of heat and electricity, and sonorous.
Physical Properties of Non-metals
Non-metals are soft, dull in appearance, brittle, poor conductors of heat and electricity, and non-sonorous.
Malleability and Ductility
Malleability is the property of beating metals into thin sheets, while ductility is the ability to draw them into thin wires.
Reaction with Oxygen
Metals react with oxygen to form basic oxides, whereas non-metals react with oxygen to form acidic or neutral oxides.
Displacement Reactions
A more reactive metal displaces a less reactive metal from its salt solution in water.
Important Formulas
Board Exam Info
In the Rajasthan Board Class 7 Science exams, this chapter typically carries around 6 to 8 marks. Questions usually include fill-in-the-blanks, true or false, differentiating between metals and non-metals, and short-answer reasons for specific uses like why electrical wires are made of copper.
Frequently Asked Questions
Copper and aluminum are used because they are ductile and are very good conductors of electricity.
Copper and aluminum are used because they are ductile metals and excellent conductors of electricity.
Which liquid metal and non-metal exist at room temperature?
Mercury is the only metal that exists as a liquid at room temperature, and Bromine is the liquid non-metal.
Why can't we store lemon pickle in an aluminum or iron container?
Pickle is acidic, and acids react with metals to produce toxic salts and hydrogen gas, which can spoil the food and damage the container.
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