The electrical resistance of metals increasing with temperature and their thermal conductivity decreasing can be explained by the behavior of electrons in a metal lattice.
Electrical Resistance Increase: At lower temperatures, metals have a regular lattice structure, and the electrons move through the lattice with minimal scattering. This results in low resistance to the flow of electric current. However, as the temperature increases, the metal lattice vibrates more vigorously, creating lattice imperfections and irregularities. These imperfections hinder the flow of electrons, leading to increased resistance. The increased lattice vibrations disrupt the smooth movement of electrons, causing them to collide more frequently and scatter, impeding the current flow and increasing resistance.
Thermal Conductivity Decrease: Thermal conductivity in metals is primarily determined by the movement of free electrons. At lower temperatures, the free electrons move through the lattice relatively freely, transferring thermal energy effectively. However, as the temperature rises, the lattice vibrations increase, which introduces more scattering sites for the electrons. These scattering events hinder the transfer of thermal energy through the metal lattice, reducing its thermal conductivity. The increased lattice vibrations cause the electrons to collide more frequently with lattice atoms, decreasing their mean free path and limiting their ability to carry thermal energy efficiently.
It is worth noting that the behavior of electrical resistance and thermal conductivity with temperature can vary depending on the specific metal and its properties. However, the general trend is that increasing temperature leads to increased resistance and decreased thermal conductivity in most metals due to the increased lattice vibrations and electron scattering.