Atomic Physics

Introduction:

Atomic physics is the one of the branches of physics which deals with the study of atoms and its complex arrangement of electrons around nucleus. Not only the study of structure of an atom, it also deals with some extraordinary functions of an atom like nuclear fission and nuclear fusion and the process of making atom bombs, etc.

Definition of an atom:

Atom is defined as the 'smallest unit of the world which cannot be further subdivided to give another complete unit'. Again, an atom has lot of definitions depending on the scientists who described the atom. Because, in the older days, there is a lack of microscopy and lack of knowledge of protons, neutrons and electrons. Based on the model created by the scientists, the definition will differ.

Dalton's Billiard ball model:

• Atoms are solid and indivisible,
• All matter is made of atoms,
• All atoms of an element are identical,
• Atoms can neither be created nor be destroyed.

Thompson's Plum - pudding model:

• Above ideas of atom are accepted and continued in the same way
• But here is the introduction of negative charges called electrons.
• Electrons spread all over the atom and atom as a positive sphere.

Rutherford's model:

• He accepted all the above criteria, except the spread of electrons in the positive sphere,
• He insisted that there is some empty space present in the sphere,
• Electrons are orbiting around nucleus,
• Nucleus is the place where positive charges got accumulated and holds the mass of an atom.

Bohr's model:

• In this model, there is an introduction of the shells (orbits) around nucleus and electrons orbiting around nucleus in these permissible orbits.

Sommerfeld's model:

• He is the introducer of the elliptical orbits which is also possible in the structure of atom.

Generalized structure of an atom:

Based on the models developed by these scientists, atom acquired some definite and general structure.

• Atom is a sphere which possess nucleus in its centre and it holds the mass of it.
• Electrons orbiting around in the permissible circular or elliptical orbits.
• Protons and Neutrons are accommodated compactly inside the nucleus and together they are called nucleons.
• An atom can created electrical charge based on the increase or decrease in the no. of electrons.