Question

Give reason for the following:

Very few alpha particle retracted their path because

Answer 1

• Discovery of the nucleus within an atom is attributed to Ernest Rutherford.
• Rutherford performed rays scattering experiment.
• This experiment was performed to know the structure of an atom.

Rays scattering experiment-

• Rutherford bombarded a thin gold foil with fast-moving alpha particles from a radioactive source.
• Each alpha particle has two protons and two neutrons, He2+.
• A movable circular zinc sulfide screen was placed after the gold foil to detect the deflections suffered by alpha particles.

Observations-

• Most of the alpha particles could pass undeflected through the gold foil.
• Some particles were deflected slightly from their path.
• A very few particles bounced back from their original path.

Explanation-

• According to Rutherford following conclusions were made.
• There is a large empty space in the gold atom due to which most of the alpha particles could pass.
• The central part of the atom is heavy and positively charged which caused the deflection of a few particles.
• This positively charged central part was the nucleus.

Hence, very few alpha particles retracted their path because the central part of the atom is heavy and positively charged.