BOHR MODEL OF AN ATOM
According to Bohr:
- Atom is electrically neutral i.e. number of Protons = number of Electrons.
- In center of an atom, a dense body called Nucleus is present.
- In Nucleus, Protons and Neutrons are present.
- P = +ve
- N = no charge.
- Outside nucleus, shells or energy levels designated as K, L, M, N ----so on are present.
- In shells Electrons revolve
- E = -vely charged
- Each shell has fixed amount of energy therefore they are called as stationary states or energy levels.
- The energy of electron is quantized.
- Only those orbits are permitted in which angular momentum of electron is integral multiple of h/2π.
- The electron in its ground state neither absorb or emit energy that is it keeps on revolving in orbit without losing any energy.
- Energy is emitted or absorbed only when electron jumps from its lower state to higher state called as excited state .The excited state being unstable, electron returns to its ground state and in doing so it emit the absorbed energy equal to:
Usefulness of Bohr model:
- It explained stability of an atom.
- It explained the spectrum of hydrogen: