Final answer:
Water is a poor conductor of heat because it is a good insulator and lacks free electrons to efficiently transfer thermal energy. In contrast, metals, with their higher number of free electrons, are better heat conductors.
Step-by-step explanation:
Water is a poor conductor of heat because it is a good insulator. Unlike metals, water does not have a large number of free electrons that can carry thermal energy. In other words, water molecules do not transfer heat as efficiently as metals do.
The (average) kinetic energy of a water molecule in a cold body is lower than in a hot body. When two water molecules collide, the molecule with greater kinetic energy does not transfer as much energy to the molecule with less kinetic energy, resulting in a slower transfer of heat. Additionally, the number of collisions and heat conduction depend on the cross-sectional area, which further limits the efficient transfer of heat in water.
In contrast, materials like metals have a higher number of free electrons, allowing them to conduct heat more effectively.