Question

Why is the first shell called K shell?

Answer 1

Hint :We know that the characteristics of an orbital are expressed in terms of Quantum numbers. These quantum numbers help in getting the complete information about all the electrons in an atom.

Complete Step By Step Answer:
Among these Quantum numbers principal quantum number (n) is the most important one it tells about the shell to which the electron belongs. It also explains the main lines of the spectrum on the basis of the electronic jumps between these shells. The various principal energy shells are designated by the letters K, L, M, N, O, P………etc.
The first shell is known as K shell.
A Spectroscopist, Charles G. Barkla gave the names to the electron shells. He studied the X-rays that were emitted by atoms when they hit the high energy electrons. He concluded that atoms appeared to emit two types of X-rays. These X-rays differ in energy and Charles originally called the higher energy X-ray type A and the lower energy X-rays type B. He later renamed these two to K and L since he realized that the highest energy X-rays produced in his experiment might not be the highest energy X-rays possible. It later turned out that K has the highest energy possible. Thus, the innermost shell was called the K- shell.

Note :
We have seen how the innermost shell was assigned the name K shell. It should be noted that the principal quantum number gives the average distance of the electron from the nucleus. Barkla won the 1917 nobel prize for his work.