03-08-2012, 11:22 AM
Atomic Structure
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The Indian philosopher, Kannad suggested that matter is made up of several small particles
called anu which cannot be broken down further.
Sommerfeld modified Bohr’s model by introducing the idea of motion of electrons in
elliptical orbits.
Schrodinger formulated a new model called quantum mechanical model of atom or wave
mechanical model of atom.
Atoms can be divided into two main parts: the nucleus and the extra-nuclear part.
Electrons, protons and neutrons are identified as fundamental particles. The nucleus of an
atom comprises protons and neutrons, and electrons are present in the extra-nuclear part.
The numbers which designate and distinguish the various atomic orbitals and the electrons
present in them are called quantum numbers. The four quantum numbers are as follows:
Principal quantum number (n)
Azimuthal quantum number (l)
Magnetic quantum number (m)
Spin quantum number (s)
The Principal quantum number determines the energy of the shell.
The Azimuthal quantum number represents the sub-shell to which an electron belongs.
The Magnetic quantum number represents the orientation of an atomic orbital in space.
The Spin quantum number represents the direction of the spin of the electrons.
The distribution of electrons in the different orbitals of an atom of an element is called
electronic configuration.