postulates of bohr atom model?
Answers
Postulates of the Bohr Atomic Model
Electrons revolve around the nucleus in a fixed circular path termed “orbits” or “shells” or “energy level.”
The orbits are termed as “stationary orbit.”
Every circular orbit will have a certain amount of fixed energy and these circular orbits were termed orbital shells. The electrons will not radiate energy as long as they continue to revolve around the nucleus in the fixed orbital shells.
The different energy levels are denoted by integers such as n=1 or n=2 or n=3 and so on. These are called as quantum numbers. The range of quantum number may vary and begin from the lowest energy level (nucleus side n=1) to highest energy level.
The different energy levels or orbits are represented in two ways such as 1, 2, 3, 4… or K, L, M, N….. shells. The lowest energy level of the electron is called the ground state.
The change in energy occurs when the electrons jump from one energy level to other. In an atom, the electrons move from lower to higher energy level by acquiring the required energy. However, when an electron loses energy it moves from higher to lower energy level.
Therefore,
1st orbit (energy level) is represented as K shell and it can hold up to 2 electrons.
2nd orbit (energy level) is represented as L shell and it can hold up to 8 electrons.
3rd orbit (energy level) is represented as M shell and it can contain up to 18 electrons.
4th orbit (energy level) is represented as N Shell and it can contain maximum 32 electrons.
The orbits continue to increase in a similar manner.
Atom has a nucleus where all protons and neutrons are present.
The size of the nucleus is very small and is present at the centre of the atom.
negatively charged electrons revolve around the nucleus.
the electrostatic force b/w nucleus and electron is equal to the centrifugal force on electron.
electrons can revolve only in those orbits in which angular momentum of electron is integral multiple of h/2pie i.e mvr=nh/2pie; n = +ve integral no. , h= planck’s const.
the orbits in which the electrons revolve are called the stationary orbits because in these orbits energy of the electrons remain const.
The emission or absorption of energy in the form of photon can only occur when electron jump from one stationary state to other.