a subsrance has an atomic number of 80. How many protons and electrons do atoms of the substance have? what is the subsance?

The substance is Mercury. It has 80 electrons revolving around nucleus and 80 protons inside nucleus.

Explanation:

Atomic number of atom represent the number of electrons and protons of the atom. Thus,

Number of electrons = number of protons = 80

The atom which has atomic number 80 in the periodic table is Mercury.