The Lewis symbol for $Ar$ atom is seen in the diagram.
Work Step by Step
RULES TO WRITE LEWIS SYMBOL - Find out the number of valence electrons in the atom. - Write the element symbol and around it present each valence electron with one dot to the top, bottom, right or left of that symbol. -Spread out the dots as much as possible (so there would be minimum electron-electron repulsions), and no spots can hold over 2 electrons. 1) $Ar$ is in group 8A, so it has 8 electrons in the outermost occupied shell. Therefore, $Ar$ has 8 valence electrons. 2) That means in the Lewis symbol, there will be 8 dots. Since each spot can hold up no more than 2 dots, 4 spots can hold up to 8 dots in maximum, with each spot holding 2 dots. Since $Ar$ has exactly 8 dots, there is only one arrangement possible, which is mentioned above: 8 dots are spread out, with 2 dots in each spot.