Science Question on How are Electrons Distributed in Different Orbits (Shells)?

Question

$Na^+$ has completely filled K and L shells. Explain

Accepted Answer

The atomic number of sodium is 11. So, neutral sodium atom has 11 electrons and its electronic configuration is 2, 8, 1. But $Na^+$ has 10 electrons. Out of 10, K-shell contains 2 and L-shell 8 electrons respectively. Thus, $Na^+$ has completely filled K and L shells.