Atoms are referring to the smallest part of an element. It shares the chemical properties with the elements and nucleus with proton, neutron, and electron. This chapter Atoms of Class 12 Physics Chapter 12, defines all basic and fundamentals about the Atoms. Students will learn about the theories and postulates based on atomic theory and its timeline progress. Based on these fundamentals students will easily grasp the important concepts of this chapter. Class 12 physics chapter 12 formulas include all important formulas and their explanation in a proper and easy way.
Some important subtopics covered in this chapter are Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom, Alpha-particle trajectory, Electron orbits, Atomic Spectra, Spectral Series, Bohr Model of the Hydrogen Atom, Energy Levels, The Line Spectra of the Hydrogen Atom, De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation
This chapter firstly defines the J.J. Thomson model of atoms and also its drawbacks. It also gives details about what it was and how it worked. Then the student will learn about the modern concept of atoms. It explains about the Rutherford experiments with alpha-particles to know the trajectory of atoms. It explains about the particles which are bombarded on the atoms. These particles have shown the change in direction after coming in contact with the atom. It also describes the orbit in which the electron moves in a molecule. It refers to the line which represents the atomic emission of an atom. The student will see the concept and effects of the series of different elements which are useful for measuring the emission.
One very important model, which is the Bohr’s model has defined the movement of the electron near the atom. He used the Hydrogen atom for performing his experiments to know about atoms and related behaviour. Although Bohr’s model is applicable only to the hydrogenic atoms means single electron type atoms. Therefore, it cannot be extended to even two-electron atoms like Helium. Students will see that the new theory referred to as quantum mechanics. It supports Bohr’s postulate. But in quantum mechanics, a given energy level may not correspond to just one quantum state.
This chapter also defines the properties, assumptions, experiments, and formulas related to the atoms.
One subtopic will outline the energy of atoms, which is recognized by how close the electron is to atom while revolving as the electron continuously loses energy and ultimately got destroyed. It will conclude the Bohr’s third postulate. Besides, this also describes the formula and structure of the hydrogen atom at the time of the experiment. In another subtopic, De Broglie’s explanation for the second postulate of Quantisation of Bohr will help students a lot. The student will study the formula and properties as well as various topic related details here. De Broglie’s hypothesis is very important as it explains the fact that electrons have a wavelength also, and hence having wave-like properties. This hypothesis gave a satisfactory explanation for Bohr’s quantized orbits by bringing in the wave-particle duality. These orbits are representing the circular standing waves.