Why are the noble gases the least reactive elements? (1 point)
Responses
They have a full valence electron shell.
They have an empty inner electron shell.
They are the elements with the smallest atomic mass.
They are the most electronegative elements.
They have a full valence electron shell.
The correct answer is:
They have a full valence electron shell.
The correct answer is: They have a full valence electron shell.
Noble gases are the least reactive elements because they have a full valence electron shell. To understand why this makes them less reactive, we need to know a few concepts about electron shells and valence electrons.
Atoms consist of a central nucleus surrounded by electrons in different energy levels or shells. The valence shell is the outermost electron shell that contains electrons involved in chemical bonding. The number of electrons in the valence shell determines an atom's reactivity.
Noble gases, such as helium, neon, and argon, have completely filled valence electron shells. For example, helium has 2 valence electrons in its first shell, which is completely filled. Neon has 8 valence electrons in its second shell, also completely filled. This stability arises from the octet rule, where atoms are most stable when they have 8 valence electrons (2 for hydrogen and helium) in their outermost shell.
Since noble gases already have their valence shells filled, they do not tend to gain or lose electrons to form chemical bonds with other elements. This makes them very unreactive under normal conditions. Noble gases are often used in applications requiring inert environments, such as in lighting or as insulation in double-pane windows.
In summary, noble gases are the least reactive elements because they have a full valence electron shell, making them stable and less likely to participate in chemical reactions.