An atom consists of a nucleus at its centre, surrounded by electrons which are revolving in different orbits. Learn about atomic structure and understand how electrons are filled in different shells.
We know that metals contain large number of free electrons. These electrons get emitted from the metal surface when sufficient heat energy is imparted to them. This phenomenon is known as thermionic emission.
Factors affecting the rate of thermionic emission :
• The nature of metal surface
• The temperature of the surface
• The surface area of the metal.
Learn about hot cathode ray tube and understand how following processes take place:
1) Thermionic emission
2) Deflection of the electron beam by the electric and magnetic fields
3) Fluorescence produced by the electron beam on a fluorescent screen.
Isotope - the atoms belonging to the same element ,having same atomic number ,but different mass number. Isobars - The atoms of different elements which have the same mass number ,but differ in their atomic number . Isotones- The atoms having different number of protons but same number of neutrons, also having different number of electrons.
Understand the phenomenon of radioactivity - It is the process of spontaneous emission of alpha, beta or gamma radiations from the nuclei of atoms during their decay. Understand the alpha, beta and gamma emission and properties of alpha, beta and gamma particles.
A SmartTest on Thermionic Emission and Radioactivity
Learnhive Lesson on Structure of an atom
Learnhive Lesson on Atomic structure