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CBSE Class 9 Science Question 9 of 34

Structure of the Atom — Question 9

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Question 9

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

Answer

The atomic number of sodium is 11. It has 11 electrons in its orbitals. So, its electronic configuration is K-2, L-8, M-1. The maximum electrons in K, L, M shells according to 2n2 rule are 2, 8 and 18 respectively.

In case of Na+ (10), one electron from the M shell is lost, and it obtains a positive charge. The new electronic configuration is K-1 and L-8. Hence, it has completely filled shells.