Question

Could someone please explain why is the electronic configuration of gadolinium 2,8,18,25,9,2 and why not 2,8,18,32,4?
Please Give a proper answer

Answer 1

Answer:

The total number of electrons in a given shell can go up to 2n^2 where n is the principal quantum number. Hence the shells can hold 2, 8, 18, 32, 50, … electrons. However, shells are made up of sub shells and not all of them may be filled. Hence, a shell could be partially filled.

Explanation:

about some of the rules for where each next electron lands, as the number of electrons increases. But the gist is that the outermost increases up to 8, then the next shell gets two, and after that internal layers start to fill up further while (mostly*) keeping two electrons in the outermost layer. These elements are known as transition metals. When these inner shell(s) are full*, the outermost starts to fill up further until that too has 8 electrons.