[Na⁺]₂[CO₃²⁻]

This represents the ionic nature of the compound, where two sodium ions (Na⁺) are bonded to one carbonate ion (CO₃²⁻).

Here's a more detailed explanation:

* Sodium ions (Na⁺): These are single atoms with a positive charge.

* Carbonate ion (CO₃²⁻): This is a polyatomic ion consisting of one carbon atom (C) bonded to three oxygen atoms (O) with an overall negative charge of 2.

The structural formula doesn't depict the exact arrangement of atoms within the carbonate ion, but rather shows the ionic bonding between the sodium and carbonate ions.

Here's a visual representation of the structural formula:

```

[Na⁺]₂ [O=C(=O)O]²⁻

```

This representation shows the carbonate ion as a central carbon atom double-bonded to two oxygen atoms and single-bonded to one oxygen atom, with the overall negative charge distributed across the ion.