Class 7 Science - HARYANA
The World of Metals and Non-metals
The chapter 'The World of Metals and Non-metals' in Class 7 Science introduces Haryana (BSEH) students to the basic classification of matter based on physical and chemical properties. Students learn about the lustrous, malleable, ductile, and sonorous nature of metals like iron and copper, contrasted with brittle non-metals like carbon and sulphur. The chapter covers essential reactions with oxygen, water, and acids, explaining concepts like rust and displacement reactions. Mastering this chapter is crucial for board exams as it forms the foundational building block for chemistry in higher classes and frequently features in descriptive questions and chemical equation identification.
Start Learning FreeKey Concepts
Physical Properties of Metals
Metals are generally hard, shiny (lustrous), 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, non-malleable, and poor conductors of heat and electricity. They can be solids, liquids, or gases at room temperature.
Reaction with Oxygen
Metals react with oxygen to form basic oxides (e.g., magnesium oxide), while non-metals react with oxygen to form acidic or neutral oxides.
Reaction with Acids and Water
Many metals react with acids to produce metal salts and hydrogen gas, which burns with a 'pop' sound. Most non-metals do not react with dilute acids.
Displacement Reactions
A more reactive metal can displace a less reactive metal from its salt solution in water, demonstrating the varying chemical reactivity of metals.
Important Formulas
Board Exam Info
This chapter typically carries around 5 to 7 marks in the Haryana (BSEH) Class 7 Science examination. Common question types include differentiating between physical properties of metals and non-metals, explaining the 'pop' sound test for hydrogen gas, and identifying products in displacement reactions.
Frequently Asked Questions
Why are electrical wires made of copper or aluminium?
Copper and aluminium are metals, which means they are very good conductors of electricity and are ductile enough to be drawn into thin wires.
Which non-metal is liquid at room temperature?
Bromine is the only non-metal that exists as a liquid at room temperature.
How can we test the nature of oxides formed by metals?
Oxides formed by metals are basic in nature, which can be tested using red litmus paper as it turns blue when dipped in their solution.
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