- As the number of electrons in both species is equal (32 electrons), they are an isoelectronic pair. - We know that the number of electrons in O, P, and S are - 8, 15 and 16 respectively and the charge in PO43− and SO42− are 3 and 2 respectively. For SO42−: 16 + (4 x 8) + 2 = 50 electrons.
