Question

Why does the thermal conductivity increases down the group in alkali metals?

Answer 1

Thermal conductivity is the ability of the material to conduct heat. It is determined largely by the free electrons. Alkali metals due to its low ionisation energy and high metallic character conducts heat well. Due to the presence of a single electron that can be easily removed from the valence shell, alkali metals act as very good conductors of heat and electricity. Conductivity increases from Li to Cs.