Argon is a noble gas. How many electrons would you expect an atom of argon to have in its outer shell?
The Correct Answer and Explanation is:
Argon (Ar) is a noble gas, which means it is in Group 18 of the periodic table. Noble gases are known for having complete and stable outer electron shells, which gives them a tendency to be chemically inert.
Argon has an atomic number of 18, which means it has 18 electrons in total. The distribution of these electrons follows the order of the energy levels, starting with the innermost shell. The electron configuration of argon is:
- 2 electrons in the first shell
- 8 electrons in the second shell
- 8 electrons in the third (outermost) shell
Thus, argon has 8 electrons in its outer shell, which makes it stable. This stable electron configuration is why argon, like other noble gases, does not readily react with other elements. The outer shell having 8 electrons is often referred to as the “octet rule,” which indicates that atoms tend to be most stable when they have 8 electrons in their outermost shell (with the exception of hydrogen and helium, which are stable with 2 electrons in their outer shell).
This complete outer electron shell is a key feature of noble gases, explaining why they are chemically unreactive. For other elements, atoms may gain, lose, or share electrons to achieve this stable configuration, but noble gases like argon already possess it naturally.
