The size of a sodium atom is typically measured by its atomic radius, which is the distance from the nucleus to the outermost electron shell.

Here are the different atomic radii for sodium:

* Covalent radius: 186 picometers (pm)

* Metallic radius: 186 pm

* Van der Waals radius: 227 pm

Note:

* Covalent radius is measured in a covalent bond between two sodium atoms.

* Metallic radius is measured in a metallic crystal lattice.

* Van der Waals radius is the distance between two non-bonded sodium atoms in a crystal lattice.

So, depending on the context, the size of a sodium atom can vary slightly.