Compounds

What is a Compound?

A Compound is a pure substance formed when two or more elements combine chemically in a fixed ratio.

Key Characteristics

1. Fixed Composition: Water ($H_2O$) is always 2 Hydrogen atoms : 1 Oxygen atom. If the ratio changes, it becomes a different substance (like $H_2O_2$).

2. New Properties: The properties of a compound are completely different from its constituent elements.

   • Hydrogen: Explosive gas.
   • Oxygen: Supports combustion (burning).
   • Water ($H_2O$): Extinguishes fire!

3. Separation: Constituents can only be separated by chemical methods (like electrolysis), not physical methods (like filtration).

Common Examples

Activity: Heating Sugar

When you heat sugar in a test tube:

1. It turns brown, then black (chars).
2. Water droplets appear on the sides.
3. Result: Sugar decomposes into Carbon (black residue) and Water. This proves Sugar is a compound.