Chapter 3 – Metals and Non-Metals
Gist of the Lesson
Elements are classified broadly into two categories on the basis of properties:
- Metals: Iron, Zinc, Copper, Aluminium etc.
- Non-Metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc.
Apart from metals and non-metals, some elements show properties of both metals and non-metals, e.g., Silicon, Arsenic, Germanium. They are called Metalloids.
Comparison of Physical and Chemical Properties of Metals and Non-Metals
| Property | Metals | Non-Metals |
|---|---|---|
| Physical State | Solid at room temperature (except mercury and gallium). | Generally exist as solids and gases (except Bromine). |
| Melting and Boiling Points | Generally high, except gallium and cesium. | Generally low, except diamond and graphite. |
| Density | Generally high. | Generally low. |
| Malleability and Ductility | Malleable and ductile. | Neither malleable nor ductile. |
| Electrical and Thermal Conductivity | Good conductors of heat and electricity. | Poor conductors, except graphite. |
| Luster | Possess shining luster. | Do not have luster, except iodine. |
| Sonorous Sound | Give sonorous sound when struck. | Do not give sonorous sound. |
| Hardness | Generally hard (except Na, K). | Generally soft (except diamond). |
Comparison of Chemical Properties of Metals and Non-Metals
Reaction with Oxygen
Metals: Form metal oxides (e.g., 4Na + O2 → 2Na2O).
Non-Metals: Form acidic oxides (e.g., C + O2 → CO2).
Reaction with Water
Metals: React to form metal hydroxides and release hydrogen gas.
Non-Metals: Do not react with water.
Reaction with Dilute Acids
Metals: React to form salts and release hydrogen gas.
Non-Metals: Do not react with acids.
Occurrence of Metals
- Minerals: Naturally occurring elements or compounds in Earth’s crust.
- Ores: Minerals containing high metal content extracted economically.
Mind Map
Metals: Solid, high melting point and boiling point, high density, malleable, ductile, good conductors.
Non-Metals: Exist in solid, liquid, gas forms, poor conductors, brittle, lower melting and boiling points.