Wednesday
April 1, 2015

Homework Help: Chemistry

Posted by Ankur on Friday, January 11, 2013 at 8:53am.

xplain why the value of the band gap energy, Eg, decreases in the following homologous series:
Cdiamond=5.4 eV; Si=1.1 eV; Ge=0.72eV; Sn=0.08 eV.


As we move down the group, bond strength increases. As the strength increases, materials become more metallic in nature, since metals are strong. Metals tend to conduct electrons more easily, hence the band gap must decrease as materials become more metallic in nature.

Bond strength increases as we move down a group in the periodic table. The increasing bond strength tightens the spread between the valence and conduction bands, which in turn lowers the band gap of the material and allows it to be more conductive.

Due to the increasing nuclear mass, the bond strength decreases as we go down the group in the periodic table, and the resulting bonds within the material are weaker, meaning they require less energy to remove electrons, leading to a smaller band gap.

Due to the increasing atomic radius, valence electrons are more weakly bound, therefore the bond strength decreases as we go down the group in the periodic table, and the resulting bonds within the material are weaker, meaning they require less energy to remove electrons, leading to a smaller band gap.

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

physics - Which of the following is correct for the energy levels in an atomic ...
Chemistry - What happens to these physical properties as the strength of ...
chemistry - please help!!! im confused... can you explain to me how period and ...
chemistry - 1 _____is defined as one-half of the distance between the nuclei of ...
Chemistry - Which of the following statements correctly describes the change ...
chemistry - 2 NO2(g) N2(g) + 2 O2(g) The ΔH for the reaction above is -66....
Chemistry - H2(g) + I2(g) 2 HI(g) The forward reaction above is exothermic. At ...
Chemistry - (a) Cadmium telluride (CdTe) is a semiconductor witha band gap, Eg, ...
Chemistry - Which trends are observed when the elements in Period 3 on the ...
Chem - Consider the exothermic reaction CoCl42-(aq) + 6 H2O(l) --> Co(H2O)62...

Members