Group 0: the noble gases

What is the name given to the group 0 elements?

The noble gases. The AQA GCSE specification says it directly: "The elements in Group 0 of the periodic table are called the noble gases." The name comes from how rarely they react with anything, like nobility keeping themselves apart. In the international 1 to 18 numbering of the periodic table, the same column is called group 18.

Group 0 elements

Boiling points are converted from the kelvin values in PubChem's periodic table. Element 118, oganesson, also sits in this column, but only a handful of atoms have ever been made, so its properties haven't been measured. Explore each element's electron arrangement in our Electron Configuration Tool.

Why are the noble gases unreactive?

Atoms react to lose, gain or share electrons until they have a full outer shell. The noble gases already have one. AQA notes that they have eight electrons in their outer shell, except for helium, which has only two (its only shell is full with two). So they have no tendency to lose, gain or share electrons, which makes them unreactive and means they don't easily form molecules. Unlike oxygen (O₂) or nitrogen (N₂), the noble gases exist as single atoms: they are monatomic.

"Unreactive" isn't quite "never reacts". OpenStax Chemistry lists a few compounds of the heavier ones, such as xenon fluorides like XeF₂ and XeF₄. Their outer electrons are further from the nucleus, so a very reactive element like fluorine can pull them into a bond. Helium, neon and argon form no stable compounds.

Group 0 trends

• Boiling point increases down the group. AQA: "The boiling points of the noble gases increase with increasing relative atomic mass." Bigger atoms have stronger forces between them, so more energy is needed to separate them.
• Density increases down the group, because the atoms get heavier.
• All are colourless gases at room temperature, and all are very unreactive.

Predicting a property from the trend

Exams often give you the data for some group 0 elements and ask you to predict another. Suppose you know krypton boils at −153 °C and xenon at −108 °C, a rise of 45 °C. If the next step down rises by a similar amount, radon should boil at about −108 + 45 = −63 °C. The real value is −62 °C, so the prediction is very close. Always say your prediction follows the trend, and give a sensible range rather than an exact claim.

Uses of the noble gases

These uses are all described in OpenStax Chemistry. For the rest of the periodic table, see our guide to the periodic table.

Common mistakes

• Saying all noble gases have 8 outer electrons. Helium has 2; its single shell is full.
• Saying boiling points decrease down the group. They increase.
• Writing noble gases as molecules, such as He₂. They exist as single atoms.
• Saying "the noble gases have no electrons". They have full outer shells, not empty ones.
• Explaining the boiling point trend with covalent bonds. There are no bonds to break; it is the forces between atoms that get stronger.

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