Despite their renowned stability and inertness, noble gases can form compounds under certain conditions, typically involving highly reactive elements or extreme conditions. The first noble gas compound discovered was xenon hexafluoroplatinate (XePtF₆) in 1962. This discovery challenged the long-held belief that noble gases are entirely inert. Xenon and krypton, being larger atoms with more electron shells, are more likely to form compounds compared to other noble gases. Compounds of xenon and krypton are often formed with highly electronegative elements, like fluorine and oxygen. For instance, xenon forms compounds like xenon difluoride (XeF₂) and xenon tetrafluoride (XeF₄). These compounds are typically created under conditions of high pressure and temperature, which can force the noble gases to react. However, it's important to note that such compounds are rare and often unstable, highlighting the general trend of minimal reactivity among noble gases.

The boiling and melting points of noble gases are among the lowest in the periodic table. This is primarily due to their atomic structure, where atoms exist as individual, monatomic entities, rather than as molecules or complex lattice structures. The forces between individual noble gas atoms are van der Waals forces, which are significantly weaker than the ionic or covalent bonds found in other elements. As a result, only a small amount of energy is required to overcome these weak interatomic forces, leading to low boiling and melting points. For example, Helium, with the weakest of these interatomic forces, has the lowest boiling and melting points of any element. This contrast is stark when compared to elements with stronger bonding forces, such as metals or ionic compounds, which require considerably more energy to change state, thus having much higher boiling and melting points.

Helium is preferred over hydrogen in balloons and airships primarily due to safety reasons. Although hydrogen is lighter and provides more lift, it is highly flammable and poses a significant fire and explosion risk. This was tragically exemplified in the Hindenburg disaster of 1937. In contrast, helium is non-flammable and safe to use. Despite providing slightly less lift than hydrogen, helium's safety advantage far outweighs this difference. Additionally, helium being inert, does not react with other materials, which is beneficial for the longevity and maintenance of the balloons or airships. These safety and stability features make helium the gas of choice for lighter-than-air craft, despite its higher cost and lower lift capacity compared to hydrogen.

Noble gases, under normal conditions, do not conduct electricity due to their complete valence electron shells and overall lack of free electrons. The complete outer shell of electrons in noble gases means that there are no loosely bound electrons available to move freely and conduct an electric current. In substances that conduct electricity, such as metals, free electrons can move through the material, allowing the flow of electrical current. However, in noble gases, the electrons are tightly bound within their respective atoms, adhering to a stable and inert configuration. This stability precludes the possibility of these electrons being readily available to conduct electricity. It is only under extreme conditions, such as high voltage or low pressure, that noble gases can become ionised and conduct electricity, typically in the form of a plasma.

Noble gases are extensively used in lighting applications due to their unique electronic configurations and resultant properties. When electricity is passed through noble gases, they emit light. This phenomenon occurs because the electric current excites the electrons in the noble gas atoms, causing them to jump to higher energy levels. When these electrons return to their original energy levels, they release energy in the form of light. The specific colour of the light emitted depends on the gas used. For instance, Neon emits a distinct reddish-orange glow, commonly seen in neon signs, while Argon produces a soft blue light. This application is possible because the full valence shell of noble gases allows electrons to be excited and return to their ground state without forming new compounds or undergoing chemical reactions. This unique characteristic makes them ideal for stable and efficient lighting solutions.