NCERT Class 9 Science Chapter 8 Journey Inside the Atom Solutions
NCERT Class 9 Science Chapter 8 Journey Inside the Atom Solutions Think It Over (Page No. 140) 1. Are atoms the smallest indivisible particles? Answer: No, atoms are not the smallest indivisible particles. Scientists discovered that atoms are made up of even smaller subatomic particles — electrons, protons, and neutrons. The discovery of electrons by J.J. Thomson (1897), protons by Rutherford, and neutrons by James Chadwick (1932) proved that atoms can be divided further. Even today, research continues, as protons and neutrons themselves are made of still smaller particles called quarks. 2. Why do electrons not fall into the nucleus even though they are attracted to protons in it? Answer: According to Bohr’s model, electrons move in fixed circular paths called stationary states or shells (K, L, M, N…). While revolving in these fixed orbits, electrons do not lose energy. Bohr introduced the concept that in a stationary state, the energy of an electron remains constant, so it neither s...