The valency of noble gas elements is _____

The correct answer is 0.
Concept:

• A periodic table is an arrangement of elements based on their atomic numbers and chemical properties.
• It is divided into 18 groups and 7 periods running vertically and horizontally respectively.
• The atoms of the elements are structured in the form of a nucleus and atomic orbitals or shells. The atomic orbitals seat the electrons.
• The electrons are arranged into the succeeding shells in definite order as 2,8,18, and so on. 
• The last shell of the atom is known as the valence shell. When an atom is short of electrons or has extra electrons from achieving a stable configuration, this valence shell loses or gains electrons.
• The number of electrons that an atom loses or gains to gain stability is identified as its valency.

Explanation:

• Inert gases are nonmetals placed at the extreme right end of the periodic table.
• They all together form the 18th group of the period table.
• They have a stable electronic configuration i.e., all of their electronic orbitals are completely filled.
• Due to their ideal electronic configuration, inert gases also go by the name noble gases.
• They have no drive to gain or lose any electrons from their valence orbitals.
• Therefore, the valency of a noble gas element is 0.

Additional Information

• The elements constituting the 18^th group are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rd).
• Electronic Configuration of Noble gases.
  • He = 1s²
  • Ne = [He]2s²2p⁶
  • Ar = [Ne]3s²3p⁶
  • Kr = [Ar]3d¹⁰4s²4p⁶
  • Xe = [Kr]4d105s25p⁶
  • Rd = [Xe]4f¹⁴5d106s26p6