Question

How do chemical properties of halogens differ from that of the noble gases?

Answer 1

To answer this question first we must know what halogens and noble gases are. Halogens are a group of elements in the periodic table belonging to group $17$ and consist of elements like fluorine, chlorine, bromine and iodine. Noble gases belong to the group $18$ of the periodic table consisting of helium, neon, argon, krypton, xenon and radon.

Complete answer:
The differences in chemical properties between the halogens and noble gases are shown below

Halogens	Noble gases
Very reactive	Non - reactive
Has seven valence electrons and needs one more to have an octet hence, they react with metals and other halogens to get an octet. When this happens, the atoms become highly stable and have noble gas configurations.	Whereas in case of noble gases, they have filled valence shells as they occur in nature. Helium has a duet of valence electrons, and the rest of the noble gases have an octet. Because of this, they are very unreactive.

Additional information:
i) Differences in physical properties between halogens and noble gases are;
ii) Halogens exist as diatomic molecules when they are in their pure form while noble gases are monatomic.
iii) Halogens are colored and have a distinctive and unpleasant odor while noble gases are colorless and odorless.
iv) Halogens exist in all three main phases of matter, fluorine and chlorine are gases; bromine is a liquid; iodine and astatine are solids. Noble gases exist as gases.

Note: A chemical property is defined as a material's properties that becomes evident during or after, a chemical reaction; which means, any quality that can be established only by changing a substance's chemical identity. Chemical properties can be used for building chemical classification. They can also be useful to identify an unknown substance or to separate or purify it from other substances.