Which noble gas has the lowest atomic number?

Helium has the lowest atomic number among the noble gases because its nucleus contains only two protons, which defines its atomic number. Atomic numbers increase as the number of protons in the nucleus increases. Helium's atomic number is 2, indicating that it has two protons. In comparison, the other noble gases like neon, argon, krypton, and xenon have atomic numbers of 10, 18, 36, and 54 respectively, with their nuclei containing more protons.