In the phosphate ion (PO₄²⁻), each oxygen atom forms a covalent bond with the central phosphorus atom. The phosphate ion has a total of four oxygen atoms bonded to the phosphorus atom, and each oxygen shares a pair of electrons with the phosphorus atom.
Since oxygen is more electronegative than phosphorus, it tends to attract electrons more strongly. As a result, the shared electron pairs in the covalent bonds are pulled slightly towards the oxygen atoms, giving them a partial negative charge (δ⁻). The phosphorus atom, on the other hand, carries a partial positive charge (δ⁺).
The phosphate ion also has two additional valence electrons (compared to a neutral phosphate atom) due to the overall charge of -2. These extra electrons are not directly bonded to the oxygen atoms but are present as a lone pair on the phosphorus atom. These lone pair electrons are not involved in bonding with other atoms.
In summary, in the phosphate ion, the oxygen atoms get their electrons from the covalent bonds they form with the phosphorus atom, and the phosphorus atom carries additional lone pair electrons to maintain the overall charge of the ion.