To draw the Lewis dot diagram for argon, we first need to know that argon is a noble gas with the atomic number 18. This means it has 18 electrons, and its electron configuration is 1s2 2s2 2p6 3s2 3p6. The outermost shell, which is the third shell in this case, contains 8 electrons—2 in the 3s subshell and 6 in the 3p subshell.
The Lewis dot structure represents only the valence electrons, which are the electrons in the outermost shell. For argon, since it has 8 valence electrons, we can represent these electrons as dots around the symbol for argon (Ar) in the following way:
Lewis Dot Structure:
Ar: • • • • • • • •
This diagram shows a pair of dots for the 2 electrons in the 3s subshell and 6 dots representing the 6 electrons in the 3p subshell. The arrangement suggests that argon has a filled valence shell, which is why it is chemically inert and does not readily react with other elements.