CBSE Class 11-science Chemistry Structure of Atom
Discovery of Sub-Atomic Particles
Mass number is the sum of protons and neutrons
Isotopes are the atoms of same element with same atomic number but different mass number.
Planck's Quantum Theory
When light of appropriate frequency is allowed to fall on a metal, electrons are found to be ejected from the metal surface. This phenomenon is called Photoelectric Effect.
The no. of photoelectrons emitted from a metal is proportional to the intensity of light.
Emission spectrum is obtained when radiations emitted by the excited substance are analysed in a spectroscope.
The Emission spectrum of hydrogen consists of large no. of lines appearing in different regions of wavelengths
According to Heisenberg's uncertainty principle it is impossible to determine simultaneously the exact position and exact momentum (or velocity) of an electron.
Electronic Configuration of Atoms
Rules for filling electrons in Orbitals are Aufbau principle, Pauli's Exclusion Principle and Hund's rule.
The extra stability of half-filled and completely-filled electronic configurations is due to 2 factors, a) Exchange energy b) Symmetrical distribution of electrons.
Quantum Mechanical Model of Atom
The solution of the Schrodinger wave equation gives us the wave function of the electron and also the probability of finding the electrons in the orbitals.
The regions of zero electron density are called nodes and the plane in which the electron density is zero is called nodal plane.
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