Class 7 Science - BIHAR
The World of Metals and Non-metals
In the chapter 'The World of Metals and Non-metals', Class 7 Bihar Board students explore the fascinating physical and chemical properties of materials around us. The chapter distinguishes shiny, hard, malleable metals like iron and copper from brittle, dull non-metals like coal and sulfur. Students learn about conduction of heat and electricity, sonority, and how these elements react with oxygen, water, and acids. Understanding this chapter is crucial for board exams as it forms the foundational basis for chemistry in higher classes and features regularly in objective and short-answer questions.
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 soft, non-lustrous, brittle, poor conductors of heat and electricity, and are not sonorous. Examples include oxygen, carbon, and sulfur.
Malleability and Ductility
Malleability is the property by which metals can be beaten into thin sheets, while ductility is the ability to be drawn into thin wires.
Reaction with Oxygen
Metals react with oxygen to form basic oxides that turn red litmus blue, whereas non-metals react with oxygen to form acidic oxides that turn blue litmus red.
Displacement Reactions
A more reactive metal displaces a less reactive metal from its salt solution in water, demonstrating the reactivity series of metals.
Important Formulas
Board Exam Info
In the Bihar Board Class 7 Science examination, this chapter typically carries around 6 to 8 marks. Questions frequently include objective multiple-choice questions (MCQs), fill-in-the-blanks about physical properties, and short-answer questions explaining why certain metals are used for specific purposes or identifying differences between metals and non-metals.
Frequently Asked Questions
Why is sodium stored in kerosene?
Sodium is an extremely reactive metal that catches fire spontaneously when it comes in contact with air and moisture. Therefore, it is stored in kerosene to prevent accidental fires.
Can non-metals conduct electricity?
Most non-metals are poor conductors of electricity, but graphite (a form of carbon) is an exception and can conduct electricity.
Why are cooking pans made of metals while their handles are made of plastic?
Metals are good conductors of heat, which helps in cooking food quickly. Plastic is a non-metal and a poor conductor of heat, preventing our hands from burning while holding the handles.
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