The EC of carbon group elements increases down the group but lead has lower EC than tin.What is the reason for that?
this source claims
( https://www.chemicalforums.com/index.php?topic=59264.0 )
tin has a weaker electron-phonon coupling than lead. So at room temperature, the conduction electrons do not get "decelerated" by the phonons as strongly as in lead. So they can move more efficiently.
Answer given by BV Narashimha Rao ,
Electrical conductivity in metals is a result of the movement of electrically charged particles. The atoms of metal elements are characterized by the presence of valence electrons - electrons in the outer shell of an atom that are free to move about. It is these 'free electrons' that allow metals to conduct an electric current. Because valence electrons are free to move they can travel through the lattice that forms the physical structure of a metal. This physical structure is deferent with deferent metals and accordingly is electrical conductivity.
The measurement for electrical conductivity is Mho whose symbol is σ (per square meter) at 20°C. This value is 8.7x1000000 For TIN and 4.87x1000000 For LEAD which is lesser than TINs Conductivity value.
The chemical arrangement of elements you cited is based on the electronic structure (density of free electrons). However, the electrical conductivity also depends of the man time (or free path) between electron collisions. Collisions are mainly due to phonons (lattice vibrations) and impurities.
The electrical conductivity in its simplest model
s = en(et/m)
where e is the electron charge, n is the density of free electrons, m is the effective mass of electrons and t is the mean free time between collisions.
Well the dear colleagues Sumit Bhowmick and Amravati Singh mentioned that tin has a weaker electron-phonon coupling than lead and therefore higher mean free time at room temperature and then higher conductivity.
Well! I add a new significant question :
Why phonon-collisions are more efficient in Lead at room temperature?
The answer should refer to the phonon spectrum and the crystalline band structure of both lead and tin.
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