Sodium azide (NaN3) is an ionic compound, meaning it's formed by the electrostatic attraction between a metal cation and a non-metal anion. Here's how to determine the outer electron arrangement:

1. Identify the ions:

* Sodium (Na): Sodium loses one electron to form a +1 cation (Na+).

* Azide (N3-): The azide ion is a polyatomic ion with a -1 charge.

2. Electron configuration of ions:

* Na+: Sodium's electron configuration is 1s²2s²2p⁶3s¹. Losing one electron leaves it with 1s²2s²2p⁶, which is the same as neon (Ne).

* N3-: The azide ion (N3-) has a total of 16 valence electrons (3 nitrogen atoms x 5 valence electrons + 1 extra electron from the negative charge). The most stable arrangement is a triple bond between the nitrogen atoms, with each nitrogen having a lone pair of electrons. This gives each nitrogen atom a total of 8 electrons in its outer shell.

3. Outer electron arrangement of sodium azide:

Since sodium azide is ionic, the outer electrons of the sodium cation are completely transferred to the azide anion. Therefore, the sodium cation (Na+) has no outer electrons, and the azide anion (N3-) has a complete outer shell with 8 electrons for each nitrogen atom.

In summary:

* Sodium cation (Na+) - No outer electrons.

* Azide anion (N3-) - Each nitrogen atom has 8 electrons in its outer shell.