Physical Properties
This section delves into the classification of elements as metals and non-metals based on their physical properties. In Class IX, students learned about different elements' roles and their properties, setting the stage for exploring their uses and significance. The key physical properties explored include:
- Metals:
- Lustre: Metals like iron, copper, and aluminum have a shiny appearance resulting from their metallic lustre.
- Hardness: Most metals are hard, although their hardness varies (e.g., sodium is soft and can be cut easily).
- Malleability: Metals can be beaten into thin sheets, a property particularly evident in metals like gold and silver.
- Ductility: Metals can be drawn into wires, with gold being the most ductile.
- Conductivity: Metals are good conductors of heat and electricity, as demonstrated by activities involving heating and electric circuits.
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Sonority: Metals produce a sound when struck, which is why they are used in instruments like bells.
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Non-metals:
- In contrast, non-metals are usually brittle, poor conductors, and can exist in solid, liquid, or gaseous states. For example, carbon, sulfur, oxygen, and hydrogen are common non-metals, each exhibiting unique physical properties that determine their use and applications.
Overall, this section emphasizes the contrasting physical characteristics of metals and non-metals, discussing their implications in everyday applications and industrial uses.