Question

Why do you think the noble gases are placed in a separate group?

Answer 1

As we know that noble gases are group eighteen elements and each one of them are independent chemical elements possessing completely filled outermost valence shells which makes these elements highly stable. They possess a very low melting point and boiling point.

Complete answer:

As we know that noble gases elements like helium, neon, argon and krypton are placed in the eighteenth group of the periodic table and they are chemically independent elements. They are very much different from the other group elements.
Let us talk about their unique properties such as noble gases elements are highly unreactive, inert meaning they do not have any tendency to lose or gain any electron and they are present naturally in extremely small concentrations in the atmosphere. They all possess the similar electronic configuration and their outermost valence shell is completely filled making them highly stable elements and therefore they do not need any other element to stabilise these elements.
Other properties of noble gases include their highest first ionisation enthalpy as it is difficult to lose an electron from the highly stable orbitals and their electron gain enthalpy is also positive as compared to other group elements. They are inert elements and thus have no electronegativity or electropositivity and they are thus not found in combined forms.
Therefore, from the above explanation we can say that the noble gases deserve to be placed in a separated group in the periodic table.

Note: Some physical properties of Noble gases include: they are monoatomic, colourless, odourless and tasteless elements and are sparingly soluble in water. They possess a very low melting point and boiling point as weak dispersion forces are present. Among noble gases Xenon has the ability to form various compounds like Xenon difluoride, Xenon hexafluoride etc.