What is the liquid drop model? Write Comparison and difference between Nucleus and Liquid Drop.
Liquid Drop Model
The liquid drop model is one of the models which explain the different properties of the nucleus. It was first proposed by George Gamow and then developed by Niels Bohr and J. A. Wheeler. According to Bohr et al the nucleus as a drop of incompressible nuclear fluid and fluid is made of protons and neutrons (nucleons), which are held together by the strong nuclear force. This is a crude model that does not explain all the properties of the nucleus, but does explain the spherical shape of most nuclei. It also helps to predict the nuclear binding energy and to assess how much is available for consumption.
The liquid drop model, developed from the observation of similar properties between a nucleus and a drop of incompressible fluid, helps explain nuclear phenomena such as the energetic of nuclear fission and the binding energy of nuclear ground levels which cannot be illustrated by the shell model. The idea of considering the nucleus as a liquid drop originally carne from considerations about its saturation properties and from the fact that the nucleus has a very low compressibility and a well defined surface. One reason for this big difference as compared with an ordinary Liquid is that the nucleons obey Fermi statistics and a nucleus is thus a quantum fluid.
Comparison between Nucleus and Liquid Drop:
- The potential barrier acts on the surface of the nucleus similarly surface tension acts on the surface of a liquid drop.
- Nuclear and Liquid drop both are in spherical shape.
- The short range force acts on both cases.
- The near constant binding energy per nucleon may be compared to the constant heat of evaporation of a liquid.
- Two small liquid drops combine to make a bag drop and a big drop breaks into small drop similar behavior shows in case of nuclear fusion and fission of nuclei.
Difference between Nucleus and Liquid Drop:
- There is positive charge (proton) present in the nucleus but not found in liquid drop.
- Nucleus contains two components like proton and neutron but not in liquid drop.
- The number of nucleons in the heaviest stable nucleus is much smaller than the molecules in an average liquid drop.