What is conduction heat transfer primarily accomplished by?

Conduction heat transfer occurs through the direct contact of molecules within a material. When molecules are closely packed, they are able to transfer kinetic energy from one to another efficiently. This transfer happens because when one molecule vibrates or moves due to heat energy, it collides with neighboring molecules, causing them to vibrate and transfer energy as well. This process continues throughout the material until thermal equilibrium is reached.

In solids, especially metals, the density and arrangement of atoms facilitate this efficient transfer of heat. The closer the molecules are to one another, the more frequent these energy-transferring collisions will be, making conduction an effective means of heat transfer in solid materials.

Other options do involve heat transfer processes but are not related to conduction. For instance, liquid movements refer to convection, gaseous diffusion also relates to convection in gases, and radiative heat exchange refers to the transfer of energy through electromagnetic waves, such as infrared radiation, which does not require direct contact between materials.