Physical Properties of Non-Metals

📚 Key Concepts

🔹 Real-Life Example

When you break a piece of sulfur or coal, it shatters into fragments rather than bending. When you try to hammer charcoal, it crumbles to powder. Non-metals behave very differently from metals – they’re often dull, brittle, and don’t conduct electricity (which is why plastic is used to coat electrical wires for safety).

Non-metals: Elements that typically lack metallic luster, are poor conductors of heat and electricity, are brittle when solid, and cannot be hammered into sheets or drawn into wires.

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🧪 Important Properties

🔸 Physical State

  • Solids: Carbon, sulfur, phosphorus, iodine
  • Liquids: Bromine (only non-metal liquid at room temperature)
  • Gases: Oxygen, nitrogen, chlorine, hydrogen

🔸 Luster

  • Generally dull appearance
  • Exceptions: Diamond (carbon) and iodine have some luster
  • Why: No free electrons to reflect light

🔸 Malleability and Ductility

  • Brittle when solid: Break or shatter when hammered
  • Cannot be drawn into wires
  • Example: Try hammering sulfur – it breaks into pieces

🔸 Hardness

  • Usually soft and brittle
  • Major exception: Diamond (hardest natural substance)
  • Uses of diamond: Cutting tools, drill bits, jewelry

🔸 Sonority

  • Do not produce ringing sounds
  • Make dull sounds when struck

🔸 Conductivity

  • Poor conductors of heat and electricity
  • Major exception: Graphite (carbon) conducts electricity
  • Use: Graphite in pencils and as electrodes

🔸 Density

  • Generally low to moderate density
  • Gaseous non-metals have very low density

🔸 Melting and Boiling Points

  • Usually low melting and boiling points
  • Exceptions: Carbon, silicon, boron (very high melting points)
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🔍 Advanced: Non-Metal Diversity

Non-metals show much greater diversity in properties than metals. They can be gases (oxygen), liquids (bromine), soft solids (sulfur), or extremely hard (diamond)!