The Lewis structure of phosphate (PO43-) is a representation of the molecule that shows the arrangement of its atoms and the bonds between them. Phosphate is a polyatomic ion with a central phosphorus atom surrounded by four oxygen atoms.
Here is the step-by-step explanation to draw the Lewis structure of phosphate:
- Count the total number of valence electrons: Phosphorus has 5 valence electrons, and each oxygen atom has 6 valence electrons. Since there are four oxygen atoms, the total number of valence electrons is 5 + (4 × 6) = 29. However, since the phosphate ion has a 3- charge, we add 3 more electrons, making the total 32 valence electrons.
- Place the central atom: Phosphorus is the central atom in the phosphate ion. Place the phosphorus atom in the center.
- Arrange the surrounding atoms: Place the four oxygen atoms around the phosphorus atom.
- Draw single bonds: Connect each oxygen atom to the phosphorus atom with a single bond. This uses up 8 electrons (4 bonds × 2 electrons each).
- Distribute the remaining electrons: After drawing the single bonds, you have 24 electrons left. Place these electrons as lone pairs on the oxygen atoms. Each oxygen atom should have 6 electrons (2 in the bond and 4 as lone pairs).
- Check for octet rule: Ensure that each atom (except hydrogen) has a full octet of electrons. In this case, phosphorus has 10 electrons, which is acceptable because it can have an expanded octet.
- Assign formal charges: Calculate the formal charges to ensure the structure is correct. The formal charge on phosphorus is 0, and each oxygen atom has a formal charge of -1, which balances the overall charge of the ion (-3).
The final Lewis structure of phosphate (PO43-) shows a central phosphorus atom with four single bonds to oxygen atoms, each oxygen atom having three lone pairs of electrons.