Question

why the diamond called an non metal even it is hard

Answer 1

metals are generally hard.but all hard objects cannot be metals.

Answer 2

The hardness of diamond comes due to the tetrahedral structure of diamond!!
Carbon element is a non metal and even though diamond in the hardest substance known,it is an allotrope of carbon and thus is A NON METAL!!

Diamond and graphite + fullerenes are allotropes of carbon,CARBON IS A NON METAL ALREADY PROVED BY THE SCIENTISTS LONG AGO!

elements which are brittle ,generally  non-conductors,non-malleable and non-ductile are called non-metals. But there are exceptions like diamond.Thus it being a non-metal

-regards
rate me up
brainiest answer :3