Question

How can you say that non-metals are bad conductors of heat??

Answer 1

Because non metal compounds do not have a metallic structure, which benefits heat conduction. Nonmetals are poor conductors of heat

Answer 2

Nonmetals are poor conductors of heat because non metal compounds do not have a metallic structure, which benefits heat conduction. A metallic structure is metallically bonded. They have a sea of delocalised, free moving electrons which are capable of conducting heat whilst these particles vibrate.