Question

Why can xenon expand its octet to form compounds but neon can't

Answer 1

Answer is: xenon has empty d orbitals (5d), d orbitals may accept electrons. Neon does not have empty d orbitals.

For example, xenon hexafluoride (XeF₆) is a compound where xenon uses d orbitals to expand its octet.

1) Neon (symbol: Ne) is an element (noble gas) with atomic number 10, which means it has 10 protons and 10 electrons.

Electron configuration of neon atom: ₁₀Ne 1s²2s²2p⁶.

2) Xenon (symbol: Xe) is an element (noble gas) with atomic number 54, which means it has 54 protons and 54 electrons.

Electron configuration of xenon atom:

₅₄Xe 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶.

Answer 2

The electrons in the outer shell of Xenon are much further away from the nucleus than the electrons in the outer shell of Neon. The Xenon electrons are much less bound to the atom than Neon, and a strong electronegative atom like fluorine succeeds in tearing off an electron.