atoms and molecules class 9 notes pdf

Atom

Atoms are the smallest particles of an element which can take reaction.

Size of an atom: Atomic radius is measured in nanometres.

Atomic radii of hydrogen atom = 1 × 10–10 m.

Molecule

It is the smallest particle of an element or compound which can exist independently.

• Molecules of an element constitute same type of atoms.
• Molecules may be mono-atomic, di-atomic […]