What are the trends in reactivity within the noble gases?

Noble gases are generally unreactive due to their full outer electron shells.

Noble gases, which include helium, neon, argon, krypton, xenon, and radon, are located in Group 18 of the periodic table. They are known for their low reactivity, which is due to their full outer electron shells. This means they have achieved a stable electron configuration and do not readily form chemical bonds with other elements.

However, there is a slight trend in reactivity within the noble gases. As you move down the group, from helium to radon, the reactivity of the noble gases increases slightly. This is because the outer electrons are further from the nucleus and are therefore less tightly held, making it easier for them to participate in chemical reactions.

For example, xenon and krypton can form compounds under certain conditions. Xenon can react with fluorine to form xenon hexafluoride (XeF6), and krypton can form krypton difluoride (KrF2). These reactions occur under specific conditions of high pressure and temperature. Radon, the heaviest noble gas, is also predicted to be able to form compounds, but this is difficult to confirm due to its radioactivity and short half-life.

In contrast, the lighter noble gases such as helium, neon, and argon are virtually unreactive. They do not form compounds under normal conditions due to their tightly held outer electrons.

In summary, while all noble gases are characterised by low reactivity due to their full outer electron shells, there is a slight increase in reactivity as you move down the group. This is due to the outer electrons being less tightly held by the nucleus, making them more available for chemical reactions.