Argon is a member of the group 18 elements on the periodic table called the noble gasses. These gasses are unique in that they all contain an octet of electrons in their valence shells naturally without the need for sharing electrons with another element through covalent bonding or forming ions. As a result, they are highly stable elements that are incredibly unreactive with other chemicals. Another property of argon that is useful is that it is a heavy, dense gas compared to atmospheric gasses like oxygen and nitrogen. We can use these properties of argon to help protect chemical reactions from atmospheric gasses by covering a chemical reaction in a flask with a blanket of argon on top. The layer of argon gas over a chemical reaction will sit there and not react with any of the chemicals in the reaction.