Question

$\huge{\tt\underline{\green{Question-}}}$

• Write about Rutherford's alpha scattering experiment.

• Write observations and conclusions too made by Rutherford.

• Attach a diagram too if possible.

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Answer 1

$\large{\underline{\sf{Rutherford's\:Alpha\:scattering\:experiment-}}}$

( Discovery of Nucleus in an atom )

Ernest Rutherford was interested in knowing the arrangement of electrons in an atom. For this, he conducted a unique experiment of scattering of positive charged Alpha particles by a gold foil.

Infact, alpha particles are nuclei of helium atom, with two units of positive charge and four units of mass. These particles are emitted by radio active elements like Radium and potassium. Fast moving alpha particles have considerable amount of energy and they can penetrate through matter to some extent.

• He used a gold foil which is very malleable element and can be stretched to extreme thin sheet.

• He bombarded the alpha particles over the gold foil which was about 1000 atoms thick.

$\large{\underline{\sf{Observations:-}}}$

This experiment gave the scientist totally unexpected results. He made following observations:

• Most of the fast moving alpha particles passed straight through the gold foil.

• Some of the alpha particles were deflected by small angles while passing through gold foil.

• Very few of the (one in every 12,000 particles) appeared to rebound it's original path.

$\large{\underline{\sf{Conclusions:-}}}$

• There should be large enough space inside the atom, so that most of the alpha particles passed away without deflection.

• There should be positively charged heavy body inside the atom, It is so that alpha particles which are positively charged themselves could be deflected by only positively charged body.

• Heavy, positively charged body should be present inside the atom at its centre. It is so because passage of alpha particles through gold foil was uniform.

• Positive charged body of atom must contain all the mass of atom also. Due to this, it becomes very heavy and deflects the alpha particles to 180°.

• Size of positively charged body must be very small because of alpha particles came to their original path. (i.e at 180°)

$\large{\underline{\sf{Diagram-}}}$

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Answer 2

Answer:

Rutherford Atomic Model – The plum pudding model is given by J. J. Thomson failed to explain certain experimental results associated with the atomic structure of elements. Ernest Rutherford, a British scientist conducted an experiment and based on the observations of this experiment, he proposed the atomic structure of elements and gave Rutherford Atomic Model.

Rutherford’s Alpha Scattering Experiment

Rutherford’s conducted an experiment by bombarding a thin sheet of gold with α-particles and then studied the trajectory of these particles after their interaction with the gold foil.

Rutherford, in his experiment, directed high energy streams of α-particles from a radioactive source at a thin sheet (100 nm thickness) of gold. In order to study the deflection caused to the α-particles, he placed a fluorescent zinc sulphide screen around the thin gold foil. Rutherford made certain observations that contradicted Thomson’s atomic model.

Observations of Rutherford’s Alpha Scattering Experiment

The observations made by Rutherford led him to conclude that:

• A major fraction of the α-particles bombarded towards the gold sheet passed through it without any deflection, and hence most of the space in an atom is empty.
• Some of the α-particles were deflected by the gold sheet by very small angles, and hence the positive charge in an atom is not uniformly distributed. The positive charge in an atom is concentrated in a very small volume.
• Very few of the α-particles were deflected back, that is only a few α-particles had nearly 180o angle of deflection. So the volume occupied by the positively charged particles in an atom is very small as compared to the total volume of an atom.

Explanation:

Hope this helps you ✌️