The gaseous element with 5 valence electrons and fewer neutrons than sodium is Nitrogen (N).

- Sodium (Na) has an atomic number of 11, meaning it has 11 protons and 11 electrons. Its most common isotope, Na-23, has 11 protons and 12 neutrons.

- Nitrogen (N) has an atomic number of 7, meaning it has 7 protons and 7 electrons. Its most common isotope, N-14, has 7 protons and 7 neutrons.

Therefore, Nitrogen has 5 valence electrons (from its 2nd energy level) and fewer neutrons than Sodium.