ATOMIC STRUCTURE

          Atomic structure is an important chapter in jee advanced in 

       both physics and chemistry. Many questions from this chapter 

       are straightforward and a good hold on concepts will help one

       to score well in modern physics too.

       

        

     Postulates of Bohr's theory

     1. The electron in the hydrogen atom can move around the 

         nucleus in a circular path of fixed radius and energy. These

         paths are called orbits.

   

     2. The energy of an electron in an orbit does not change with 

         time. However electrons can move between different orbits.

     3. Angular momentum is quantised.

  

     Quantum numbers:

     1. Only n,l,m were derived from Schrodinger's equation.

    
     2. Energy is decide by both n,l.

     
     3. An electron in an orbital with quantum number 'm' has a z

    component of angular momentum = m* reduced Planck constant

    
     4. When lines of hydrogen spectrum were observed using high 
         resolution, they were observed to be closely spaced doublets.
         This was the first experimental evidence for spin.
         
     Wave particle duality

     1. An important thing to remember is this is not exhibited by 
         macroscopic objects. If the De broglie formula is used, we get                a value for wavelength which is not possible.

     

  IMPORTANT GRAPHS

         

     Orbitals

     1.  s orbitals are spherical in shape, hence it does not possess an
          angular term in the wave function.
    
     2.  p orbitals are dumbbell shaped. d orbitals are double dumbell
          shaped.
  
     3. In case of p,d orbitals , those with opposite magnetic quantum
         numbers interfere with each other to form standing waves.
         ( note that wave function(psi) also represents a standing
           wave)

     4. Angular part of all s orbitals are same.

     5. Spacing between energy levels increase as mass of particle 
         decreases and space to which particle is confined decreases.
         ( if you wish to understand the meaning of this, pl read the
           derivation of particle in a box. It is not in the syllabus!!)

     6. s orbital electrons penetrate the nucleus the most.


     Other important points: Uncertainty principle, electronic 
     configuration, Pauli' exclusion principle, Hund's rule

     Thank you for reading this post and always remember

  CHEMISTRY IS EASY

             

     

    SOME EXTRA POINTS