Question

$\mathrm{Na}$ (Sodium) has completely filled K and L shells, Explain.

Answer 1

• Atomic number of Sodium ($\mathrm{Na}$) =11
• No of electrons = 11
• As per Bohr-Bury scheme, K-shell ( n = 1) can have maximum electrons = $2{\mathrm{n}}^2$ = $2*1^2$ = $2$
• As per Bohr-Bury scheme, L-shell ( n = 2) can have maximum electrons = $2{\mathrm{n}}^2$ = $2*2^2$ = $8$
• The remaining one electron will enter into the M -shell (n=3) .
• Therefore, K and L shells of sodium atoms are completely filled.