Collective model, also called unified model, **description of atomic nuclei that incorporates aspects of both the shell nuclear model and the liquid-drop model to explain certain magnetic and electric properties** that neither of the two separately can explain.

Contents

- 1 What are the achievements of collective model?
- 2 How does collective model help in understanding the nuclear fission?
- 3 What is collective model of Bohr and mottelson?
- 4 What is nuclear model in physics?
- 5 What is a collective model?
- 6 Which is magic number?
- 7 What is theory of fission?
- 8 Which model can explain nuclear fission?
- 9 What is four wheeler theory of nuclear fission?
- 10 What is the difference between liquid drop model and shell model?
- 11 What is Fermi gas model?
- 12 Do electrons contribute to the mass of an atom?
- 13 Why is it called a nuclear model?
- 14 Why do we need a nuclear model?
- 15 What is nuclear structure?

## What are the achievements of collective model?

In addition to fission, the Collective Model has been very successful in describing a variety of nuclear properties, especially energy levels in nuclei with an even number of protons and neutrons. These even nuclei can often be treated as having no valence particles so that the Shell Model does not apply.

## How does collective model help in understanding the nuclear fission?

In addition to individual nucleons changing orbits to create excited states of the nucleus as described by the Shell Model, there are nuclear transitions that involve many (if not all) of the nucleons. For higher barriers, it takes a nuclear reaction to induce fission.

## What is collective model of Bohr and mottelson?

Vibrational and rotational motions of a nucleus can be described as time-evolutions of a self-consistent mean field. This is the key idea of the collective model of Bohr and Mottelson, which opened up a new field of contemporary physics, quantum many-body theory of nuclear collective dynamics.

## What is nuclear model in physics?

Nuclear model, any of several theoretical descriptions of the structure and function of atomic nuclei (the positively charged, dense cores of atoms). Each of the models is based on a plausible analogy that correlates a large amount of information and enables predictions of the properties of nuclei.

## What is a collective model?

Collective model, also called unified model, description of atomic nuclei that incorporates aspects of both the shell nuclear model and the liquid-drop model to explain certain magnetic and electric properties that neither of the two separately can explain.

## Which is magic number?

The seven most widely recognized magic numbers as of 2019 are 2, 8, 20, 28, 50, 82, and 126 (sequence A018226 in the OEIS). For protons, this corresponds to the elements helium, oxygen, calcium, nickel, tin, lead and the hypothetical unbihexium, although 126 is so far only known to be a magic number for neutrons.

## What is theory of fission?

Fission is the splitting of an atom to form two complete smaller atoms. When a large unstable nuclide splits into two smaller stable nuclides, the combined binding energy holding each of the smaller nuclides together is less than the energy needed to hold the larger nuclide together and the surplus energy is released.

## Which model can explain nuclear fission?

The liquid-drop model of the nucleus accounts quite well for the general collective behaviour of nuclei and provides an understanding of the fission process on the basis of the competition between the cohesive nuclear force and the disruptive Coulomb repulsion between protons.

## What is four wheeler theory of nuclear fission?

Bohr and J. A. Wheeler put forward the theory of nuclear fission in 1939. The theory is based on the liquid drop model of the nucleus. On the basis of this theory, it is possible to calculate the activation energy and critical energy for fission of different nuclei.

## What is the difference between liquid drop model and shell model?

~ Shell Model is same as the atomic model where electrons arrange themselves into shells around the nucleus, whereas The Liquid Drop Model is a description of atomic nuclei in which the nucleons (neutrons and protons) behave like the molecules in a drop of liquid.

## What is Fermi gas model?

The Fermi gas model defines properties of a system of non-interacting fermions in an infinite potential well. The model predicts gross properties of various quantum-mechanical systems, for example electrons in metals, or nucleons in nuclei.

## Do electrons contribute to the mass of an atom?

Electrons are much smaller in mass than protons, weighing only 9.11 × 10^{–}^{28} grams, or about 1/1800 of an atomic mass unit. Therefore, they do not contribute much to an element’s overall atomic mass.

## Why is it called a nuclear model?

Rutherford’s model of the atom is called the nuclear atom because it was the first atomic model to feature a nucleus at its core.

## Why do we need a nuclear model?

The nuclear models throw light on the qualitative behavior of a nucleus under various experimental conditions. They help in understanding the theoretical basis for nuclear structure. This form is applicable to certain ground-state properties of most nuclei, and provides the basis of the shell characteristics of nuclei.

## What is nuclear structure?

Nuclear structure studies the properties of nuclei in isolation (for interactions between nuclei and radiation, see nuclear reactions), such as nuclear mass, characteristic energy levels, and radioactive decay modes.