TOPIC: ATOMIC STRUCTURE
1) Name the model that displaced Thomson’s model of an atom.
2) Was this model able to explain the stability of an atom? Explain the
salient features of this model.
3) Zain wants to know how electrons are able to maintain their position in
the orbits. Help him to understand the reason behind this.
Answers
Answer:
Explanation:
1. Popularly known as the plum pudding model, it had to be abandoned (1911) on both theoretical and experimental grounds in favour of the Rutherford atomic model, in which the electrons describe orbits about a tiny positive nucleus.
2. Niels Bohr explained the stability of the atoms through the concept of revolution of electrons in different energy levels. The change in the energy of an electron occurs when it jumps from a lower energy level to a higher energy level or vice versa. ... In this way, energy is not lost and the atom remains stable.
3. Electron are depending on the external factor .
1) Rutherford's model of atom displaced Thomson’s model of an atom.
2) Rutherford's model was unable to explain the stability of an atom.
The salient features of this model are as follows:
(i) The atom contains a central part called nucleus which is surrounded by electrons.
(ii) The nucleus of an atom is positively charged.
(iii) The size of the nucleus is very small as compared to the atomic size.
(iv) The mass of an atom is mainly concentrated within its nucleus.
(v) Atom as a whole is electrically neutral, i.e., number of protons inside the nucleus of an atom and the number of electrons surrounding it are equal.
(vi) Nucleus is dense and hard and most of the atom is hollow.
(vii) To explain that the electrons do not fall into the nucleus because of attraction, Rutherford said that electrons were not stationary but were revolving around the nucleus in certain circular orbits. The force of attraction is balanced by the centrifugal force which comes into play due to revolution.
3) Electrons in each orbital contain a set quantity of energy. As long as an electron remains in the same orbital, the energy content of that electron remains constant. Electrons can move between orbits by releasing or absorbing energy. The electron is constantly interacting with the nucleus via "virtual particles/photons" and the opposite electric charge of the nucleus creates a force that attracts the electron towards the nucleus.