Final answer:
The noble gases, such as helium, neon, argon, krypton, xenon, and radon, are a family of elements in group 18 of the periodic table. They are considered non-reactive because they have filled valence shells, which provide them with stable electron configurations. However, it was discovered in 1962 that these gases can form compounds under certain conditions.
Step-by-step explanation:
The noble gases are a family of elements on the periodic table, specifically in group 18. This family includes helium, neon, argon, krypton, xenon, and radon. They are called noble gases because they were initially believed to be non-reactive due to their filled valence shells. However, in 1962, it was discovered that these gases can form compounds under certain conditions.
Helium, the first noble gas, is non-reactive because it has a filled valence shell with 2 electrons. The other noble gases, with filled valence shells containing 8 electrons, were also believed to be non-reactive. This is because their full valence shells provide them with stable electron configurations, making it difficult for them to gain, lose, or share electrons with other elements. This stability is what makes them non-reactive or unreactive.
When an electric current is passed through the noble gases, they can emit colorful light. This phenomenon is used in neon lights, where neon gas emits a red light when an electric current is passed through it. This is because the electric current excites the electrons in the gas and when they return to their ground state, they release energy in the form of light.