Question

Why is aluminium a bad conductor?

Answer 1

Hint: Aluminium has three electrons in its outermost orbit, thus it has more free electrons than other elements in the periodic table. In comparison to other metals, it can be considered as a poor conductor of heat and electricity.

Complete answer:
Aluminium is a bad conductor of heat and electricity in comparison with other metals such as gold, silver and copper. Overall aluminium is a good conductor of heat and electricity.
As aluminium has three electrons in free state, it shows good conductivity for electricity and heat, but as it is less dense than copper its conductivity is lower.
Noble metals like gold and silver are far more conductive of electricity, but they are expensive so they cannot be used in daily life products. Copper has lesser conductivity but it is way cheaper than gold and silver, thus it is widely used in household products.
Although aluminium is a bad conductor of electricity relative to copper, it is cheaper than copper and thus it is also used in daily life products sometimes. Another reason to use aluminium over other metals is that it has low density and high resistance to corrosion.
Insulated power supply cables use aluminium as it is cheaper and has low density, also heat sinks for semiconductors are also made up of aluminium as it has relatively more conductivity for heat than copper.

Note:
The answer here should be considered as relative and not in the form of directness, aluminium is a good conductor, but not relative to other metals. Also aluminium has its own benefits, despite being relatively poor conductor it is still widely used.