Beginner Topic 666 of 1102 Inorganic Chemistry
Noble Gases
Group 18 elements have full outer shells and are generally unreactive.
In-depth explanation of Noble Gases
The noble gases, helium, neon, argon, krypton, xenon and radon, form Group 18 and have complete outer shells, ns2 np6, with helium having 1s2. This filled shell makes them monatomic and very unreactive, and their ionization energies are among the highest in the periodic table. Their boiling points rise down the group because the atoms are more polarizable, which gives stronger London dispersion forces. Helium has the lowest boiling point of any element, about 4.2 K at atmospheric pressure. Argon makes up about 0.93 percent of dry air and is obtained by fractional distillation of liquid air.
Going deeper: Noble Gases
Key ideas: Group 18, filled shells: He 1s2, others ns2 np6. Ionization energies are the highest in each period (He 2372 kJ per mol). Boiling points rise down the group from 4 K for He to 211 K for Rn due to London forces. He has the lowest boiling point of any substance and does not solidify at atmospheric pressure. Obtained by fractional distillation of liquid air, except He which comes from natural gas wells.
Common mistakes and connections: Students think noble gases are chemically inert with no exceptions, but Xe, Kr and Rn form compounds with F and O. Atoms are monoatomic, so the term molecule is a stretch, and atomic radii listed are van der Waals radii, which look larger than halogen covalent radii. Links to ionization energy, xenon compounds and intermolecular forces.
Visualization of Noble Gases
Boiling points rise down Group 18 from 4.2 K (He) to 211 K (Rn) as atoms become more polarizable. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Liquid helium boils at about 4.2 K, which is why it is used to cool superconducting magnets.
Frequently asked questions about Noble Gases
What is Noble Gases?
Group 18 elements have full outer shells and are generally unreactive.
Is Noble Gases a beginner, intermediate or advanced topic?
Noble Gases is a beginner topic in Inorganic Chemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Noble Gases?
Study these earlier topics in Inorganic Chemistry first: Interhalogen Compounds, Oxoacids of Chlorine, Bleaching Powder.
What comes after Noble Gases?
The next topics in Inorganic Chemistry are Xenon Compounds and Uses of Noble Gases.
Can I practise Noble Gases with quizzes?
Yes. The interactive lesson includes a self-check question on Noble Gases, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Noble Gases fits in Inorganic Chemistry
Noble Gases is topic 51 of 113 in Inorganic Chemistry.