Noble gases — Science definition
The Group 18 elements with full valence shells, which makes them extremely unreactive.
Where it is taught
- The Periodic Table — Atoms, Electrons & Periodicity, Physical Science: Chemistry, Grade 11
In use
And the noble gases (Group 18) have complete valence shells, which leaves them famously unreactive — useful precisely because they refuse to react.
The Periodic Table
Questions using noble gases
Problem 1
Answer and explanation
Its first shell is filled by two electrons. The relevant pattern is a filled available valence shell, not a requirement for eight in every element.
Main-group columns often share an outer-shell electron pattern. Group 1 typically has ns¹ and Group 17 ns²np⁵; Group 18 has a filled outer shell, with helium’s 1s² as a key exception to an eight-electron slogan. Transition elements require more attention to nearby d states and variable oxidation numbers. The pattern helps predict likely bonding behavior, but it does not prescribe an atom’s objective or supply a complete reaction energy calculation.
Its first shell is filled by two electrons. The relevant pattern is a filled available valence shell, not a requirement for eight in every element.
Response criteria
- Interpret labels, structures, axes, units and directions correctly.
- Explain the chemistry relationship or mechanism.
- Respect stated assumptions and distinguish observation from inference.
Problem 2
Answer and explanation
Noble gases have full outer electron shells (eight valence electrons, or two for helium). A full valence shell is very stable, so they have little tendency to gain, lose, or share electrons, which makes them almost completely unreactive.