(a) Which popular experiment is shown in the figure?
(b) List three observations of this experiment
(c) State conclusion drawn from each observation of this experiment
(d) State the model suggested on the basis of the above experiment.
Answers
a)Rutherford's Atomic Model.
b) 1: Almost all particles passed through the foil un-deflected.
2: Out of 20000 particles,only a few were deflected at fairly large angles.
3: A few bounced back on hitting the gold foil.
c)1: Since most of the particle passed through the foil ,therefore most of the volume occupied by an atom is empty.
2: The deflection of a few particles proved that there is a ' center of positive charges' in an atom, which is called ' nucleus' of an atom.
3: The complete rebounce of a few particle show that the nucleus is very dense and hard.
4: Since a few particle were deflected it shows that the size of the nucleus is very small as compared to the volume of an atom.
5:The electron revolve around the nucleus.
6: An atom as a whole is neutral, therefore the number of electrons in an atom is equal to the number of protons.
7: Except electrons,all other fundamental particles that lie within a nucleus are known as nucleons.
d)1: According to classicle theory,electrons being the charged particles should release or emit energy continously and they should ultimately fall into the nucleus.
2: If the electrons emit continously,they should forma continous spectrum but in fact,line spectrum was observed.
I Hope You Understand.
Explanation:
(a) This figure shows scattering of alfa-particles by a gold foil (Rutherford’s experiment).
(b) Observations:
(i) Most of the a-particles passed straight through the gold foil.
(ii) Some of the a-particles were deflected by the foil by small angles.
(iii) One out of every 12000, particles appeared to rebound.
© Conclusions:
(i) Most of the space inside the atom is empty.
(ii) The positive charge of the atom occupies very little space.
(iii) All the positive charge and mass of the atom is present in a very small volume within the atom.
(d) Rutherford’s Model of atom:
(i) There is positively charged centre in an atom called the nucleus which contains the whole mass of the atom.
(ii) The electrons revolve around the nucleus.
(iii) The size of the nucleus is very small as compared to the size of the atom.