Bohr’s model of the atom Niels Bohr proposed the following postulates regarding the model of the atom. (i) Only certain orbits known as discrete orbits of electrons are allowed inside the atom. (ii) While revolving in these discrete orbits, the electrons do not radiate energy. These discrete orbits or shells are shown in the following diagram. The first orbit (i.e., for n = 1) is represented by letter K. Similarly, for n = 2, it is L − shell, for n = 3, it is M shell and for n = 4, it is N shell. These orbits or shells are also called energy levels. − − Question 5: Compare all the proposed models of an atom given in this chapter. Thomson’s Rutherford’s Bohr’s model model model An atom An atom are consists of consists of a only a positively positively certain charged charged orbits sphere with particles known as electrons concentrated discrete embedded at the centre orbits in it. known as the inside the nucleus. The atom in size of the which nucleus is electrons very small as revolve compared to around the size of the the atom. nucleus. The electrons Electrons revolve do not around the radiate nucleus in energy well-defined while orbits. revolving.
Bohr’s model of the atom Niels Bohr proposed the following postulates regarding the model of the atom. (i) Only certain orbits known as discrete orbits of electrons are allowed inside the atom. (ii) While revolving in these discrete orbits, the electrons do not radiate energy. These discrete orbits or shells are shown in the following diagram. The first orbit (i.e., for n = 1) is represented by letter K. Similarly, for n = 2, it is L − shell, for n = 3, it is M − shell and for n = 4, it is N − shell. These orbits or shells are also called energy levels. Question 5: Compare all the proposed models of an atom given in this chapter. Thomson’s model Rutherford’s model Bohr’s model An atom consists of a positively charged sphere with electrons embedded in it. An atom consists of a positively charged particles concentrated at the centre known as the nucleus. The size of the nucleus is very small as compared to the size of the atom. The electrons revolve around the nucleus in well-defined orbits. are only certain orbits known as discrete orbits inside the atom in which electrons revolve around the nucleus. Electrons do not radiate energy while revolving.