Term symbols are a shorthand method used to describe the energy, angular momentum and spin multiplicity of an atom in any particular state. The general form is given as: Where the letter L corresponds to the angular momentum quantum number and may be assigned as S, P, D, F, G ,…….for ILI = 0, 1, 2, 3,4,…. respectively. The superscript a is called the spin multiplicity and is equal to 2S+1 , where S is the spin quantum number (= 1/2*number of unpaired electrons). The subscript J corresponds to Russel-Suanders coupling and can have values from L+S, L+S-1, L+S-2, L+S-3….L-S .           The number of microstates (N) of a system corresponds to the total number of distinct arrangements for ‘e’ number of electrons to be placed in ’n’ number of possible orbital positions. For a set of p orbitals n=6, since there are two positions in each orbital. Therefore, We can introduce the idea of a hole formalism which states that for many electronic properties one may consider

Some of the chemical elements exist in more than one different structural forms maintaining the same physical state. These different forms of a single element within the same phase are known as allotropes or allotropic forms and the property by virtue of which allotropes are formed is known as allotropy or allotropism. All the allotropes of an element exist with the same building block,  but the way in which the  building blocks are arranged in these forms are different. In other words, they have distinct crystalline forms. It should be noted that the term allotropy is used for elements only and not for compounds. Allotropes of Sn When a bar of tin is bent, a crackling sound known as the "tin cry" can be heard from the twinning of the crystals. Tin melts at the low temperature of about 232 °C (450 °F), the lowest in group 14. 1) Alpha or Grey Tin Tin exists in this form at low temperatures, below 13.2°C. It has a cubic crystal structure similar to silicon and ge

WHAT IS IT? The elements after Au (gold) in the periodic table have as their most stable oxidation state one which is 2 less than the group valency.  Although  the common oxidation state for elements in group 14 is +4, most elements in the group can also exist in oxidation state of +2.  Thus, Pb has as its most stable oxidation state the Pb(II) state, although Pb is in group 14. This is referred to as the ‘inert pair’, and is thought to be due to increased electronegativity caused by relativistic effects.  REASON The effect occurs when electrons are pulled closer to the nucleus, making them more stable and more difficult to ionize. In heavy atoms, such as those of Sn, Sb, Tl, Pb and Bi, some outer-shell electrons are not as well shielded as those in the inner core.  They are therefore sucked into the inner core of electrons and thus become inert. These metallic elements do not always show their maximum oxidation states, rather they form compounds where the oxidation sta