Devender

Let us talk today about how heat conduction occur and why metals are good heat conductors. Heat is energy that can be transferred from hotter to colder body and can be quantified from temperature. But then obvious question is how does this energy transfer takes place? In this discussion, we will only focus on transfer of heat only via conduction and do not take into consideration radiation phenomenon.  At microscopic level, we can quantify heat as motion of atoms. Hotter the body is, more kinetic energy the atoms have (they are shaking vigorously). Now, when you put a hotter body in contact with a colder body, atoms in hotter body which are moving vigorously start to shake the atoms of colder body in contact. This leads to transfer of kinetic energy (vibration of atoms in solids) from hotter body to colder body and thus transfer of heat.  For metals, you also have electrons which are free, so both electrons and atoms will acquire kinetic energy. In fact, both electrons and atom

In the last post , I discussed the difference in bonding between metals and ceramics, and how that is manifested in different properties exhibited by metals and ceramics. Now, let us try to understand why metals actually conduct electricity. The reason again ties down to bonding in metals. Like, I explained here , metals typically exhibit metallic bonding in which all the valence electrons are shared by all the atoms. There is a delocalization of electrons, unlike in covalent and ionic bonds which confine electrons only to neighboring atoms. Now, when an external electric field is applied to metals, these delocalized electrons are easy to move and thus conduct. This simple explanation is basis for Drude Model where Drude actually derives simple quantitative formula for conductivity. This explanation and thus theory is very elementary and is not be able to give correct quantitative numbers for many other properties (heat capacity and seebeck coefficient) of metals. A more detailed th

Recently, I have decided to change the blog to more science oriented. I have started a podcast ( link ) where I have decided to share my understanding of various topics in science. I will try to post 3-4 posts a week on topics related to science. So, for this post let's discuss why certain solids are metals and some ceramics. Solids, in general, can be distinguished as metals, ceramics and polymer. I am keeping the focus on difference between metals and ceramics and not going to discuss polymers in this post. If you checked my last post, matter exist in form of solid due "bonds" which keep atoms together in solid. I discussed three forms of bonds- metallic, covalent and ionic. Metals typically have metallic bonding, which is a delocalized bond where all the valence electrons are shared by each and every atoms. In contrast, covalent and ionic bonds are localized between neighborliness atoms. Atoms in ceramics typically are bound by covalent and ionic bonds. This is the