Question

Na+ has completely filled K and L shells. Explain

Answer 1

The atomic number of sodium (Na) is 11. Its electronic configuration is 2, 8, 1. It represents that there are 2 electrons in K-shell, 8 electrons in L-shell and 1 electron is M-shell.

When sodium atom loses 1 electrons, it becomes sodium ion Na+ which has 10 electrons. It has 2 electrons in K-shell and 8 electrons in L-shell. K-shell (n=1) can have maximum 2 x 1^2 = 2 electrons and L-shell (n = 2) can accommodate maximum 2 x 2^2 = 8 electrons.

Therefore, Na+ has completely filled K and L- shells.

Answer 2

Hi there !!





Atomic number of the element = Z  = 11

No: of protons is equal to the atomic number = 11

Also ,

No: of electrons = 11

Thus , electronic configuration is as follows :
K shell = 2
L shell = 8
M shell = 1

2 , 8 , 1



But , here in this case , Sodium loses one electron (Na⁺)

So , no: electrons= 10

Thus the electronic configuration becomes :

K shell = 2 electrons

M shell = 8 electrons.

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The number of electrons that can be accommodated in a given shell is given by the formula 2 n² , where n is the orbit number.

K shell :
orbit number = 1
Maximum electrons that can be accommodated = 2n² = 2 * 1² = 2 electrons

ALso , 

L shell 

orbit number = 2

Maximum electrons that can be accommodated = 2n² = 2 *2² = 8 electrons.

Hence ,
Sodium (Na⁺) has completely filled K and L shells