Question
Argon atoms has 18 electrons. How many energy shells or orbits are incomplete ? How many energy shell it contains?
Solution
Distribution of 18 electrons in argon atom is as follows:
K-shell = 2 electrons
L-shell = 8 electrons
M-shell = 8 electrons
K-shell and L-shell have maximum capacity of 2 and 8 electrons respectively. M-shell has a capacity of 18 electrons. Since, it is the outermost orbit and there is a rule that ‘the maximum number of electrons that can be accommodated in the outermost orbit is 8’. In the present case, M-shell is also complete. Thus, in argon atom, no shell is incomplete. Argon atom has three energy shells.
