Molecules of Compound

Molecules of Compounds

Definition

1. Atoms of various elements combine in definite proportions to create a compound molecule.
2. Examples of Compound Molecules

Compound	Elements Involved	Combining Ratio by Mass
Water (H₂O)	Hydrogen, Oxygen	1 : 8
Ammonia (NH₃)	Nitrogen, Hydrogen	14 : 3
Carbon Dioxide (CO₂)	Carbon, Oxygen	3 : 8

Important Notes

1. Elements vs Compounds
1. Molecules of Elements:
1. Atoms of same element combine together.
2. Each molecule of an element contains a fixed number of atoms (for example, O₂, H₂, N₂).
3. Mass ratio ka concept nahi lagta, kyunki same element hai.
2. Molecules of Compounds:
1. Atoms of different elements combine together.
2. Atoms combine in definite proportion by mass (Law of Definite Proportions).
3. Example: H₂O → Hydrogen : Oxygen = 1 : 8
2. Law of Definite Proportions
   1. The elements in a compound always join together in a definite ratio by mass.
   2. If the ratio changes, it does not form the same compound.
3. Quick Mass Ratio Examples:
   1. Water (H₂O) → Hydrogen : Oxygen = 1 : 8
   2. Ammonia (NH₃): Nitrogen and Hydrogen combine in a mass ratio of 14 : 3
   3. Carbon Dioxide (CO₂): Carbon and Oxygen combine in a mass ratio of 3 : 8

✅ Summary

1. Elements: Fixed number of atoms per molecule.
2. Compounds: Fixed mass ratio of different elements.
3. Always remember: Ratio of atoms (elements) or mass (compounds) is definite.

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