點樣分辦covalent substance?

covalent substance..... never heard of it.
only consider "ionic compounds" and "covalent compounds".

for metals like Ag, it can conduct electricity it both solid and liquid state.

for ionic compounds like LiOH, PbBr2 and NaCl, it can conduct electricity only when it's melted or dissolved in water.

for covalent compounds like CCl4, CO2 and SiO2, it cannot conduct electricity no matter in solid, liquid or dissolved from.
(except when some of them dissolved in water, like CO2 ------> carbonic acid, HCl ------> hydrochloric acid, NO2 ------> nitric acid and nitrous acid)


if you're asking about something else, or you want to add something, put it under this question.

ionic compounds are compounds that cosist of metal and non-metal ions

covalent substances .........?

covalent compounds are compounds that cosist of non-metal atoms only