Class 7 Science - PUNJAB
The World of Metals and Non-metals
The chapter 'The World of Metals and Non-metals' in Class 7 Science introduces students to the fascinating classification of elements based on their physical and chemical properties. Students explore how metals like iron, copper, and aluminium are hard, shiny, malleable, and good conductors of heat and electricity, whereas non-metals like sulphur, carbon, and oxygen lack these properties and are generally brittle and poor conductors. Understanding these differences is crucial for Punjab (PSEB) board exams as it forms the foundation of chemistry, helping students answer conceptual questions, differentiate materials used in daily life, and understand simple chemical reactions.
Start Learning FreeKey Concepts
Physical Properties of Metals
Metals are generally solid, shiny (lustrous), hard, 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 can be solids, liquids, or gases, are dull in appearance, brittle, and poor conductors of heat and electricity.
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.
Conduction in Metals
Metals allow heat and electricity to pass through them easily because of their internal structure, making them useful for cooking utensils and electric wires.
Reaction with Oxygen
When metals react with oxygen, they form basic metallic oxides, whereas non-metals react with oxygen to form acidic or neutral non-metallic oxides.
Important Formulas
Board Exam Info
This chapter typically carries around 5 to 7 marks in the Punjab (PSEB) Class 7 Science examination. Questions frequently include differentiating between metals and non-metals based on physical properties, short reasoning questions (e.g., why wires are made of copper), and fill-in-the-blanks.
Frequently Asked Questions
Why are electric wires made of copper or aluminium?
Copper and aluminium are metals, which means they are good conductors of electricity and are ductile, allowing them to be easily 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.
Can all metals be beaten into sheets?
Most metals are malleable and can be beaten into sheets, but sodium and potassium are very soft metals and cannot be hammered into sheets easily.
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