Metals and Non-Metals | Year 7 Chemistry (Cambridge) PDF Download

Introduction

• Materials around us are broadly classified into metals and non-metals based on their properties.
• Metals exhibit specific characteristics like malleability, conductivity, and luster, whereas non-metals lack these properties.

Metals

• Definition: Metals are materials that possess characteristic physical properties.
• Examples: Iron, gold, aluminum, copper.
• Physical Properties:
  • Malleability: Ability to be hammered into thin sheets (e.g., aluminum foil).
  • Conductivity: Ability to conduct heat and electricity (e.g., copper wires).
  • Sonorous: Produce ringing sounds when struck (e.g., bells made of brass).
  • Lustrous: Shiny and reflective due to smooth surfaces.
  • Ductility: Ability to be drawn into wires (e.g., copper wires).
• Uses:
  • Used in machinery, construction (e.g., steel), electrical wiring (e.g., copper wires), and ornaments (e.g., gold and silver jewelry).

Non-Metals

• Definition: Materials lacking typical metallic properties.
• Examples: Sulfur, carbon, phosphorus, oxygen.
• Physical Properties:
  • Brittle or soft: Can be easily crumbled into powders (e.g., sulfur).
  • Poor conductors: Do not conduct electricity or heat well (exceptions like graphite).
  • State: Can be solids (e.g., sulfur), liquids (e.g., bromine), or gases (e.g., oxygen).
  • Luster: Lack metallic shine and are dull in appearance.
  • Sonorous: Do not produce ringing sounds when struck.
  • Malleability and ductility: Not malleable or ductile.
• Uses:
  • Essential for life (e.g., oxygen), agricultural purposes (e.g., nitrogen as fertilizer), and industrial applications (e.g., sulfur in chemical processes).

Comparison

Metals vs Non-Metals:

• Metals are malleable and ductile; non-metals are brittle.
• Metals conduct heat and electricity; non-metals are poor conductors.
• Metals are shiny (lustrous); non-metals lack luster.

Conclusion

Understanding the differences between metals and non-metals helps in appreciating their diverse applications in everyday life and industry.