Question

What is the maximum number of electrons in an atom in which the last electron, filled, has the following quantum number? n=3

Answer 1

Hint : Except for hydrogen, all atoms have multiple electrons. The number of electrons in a neutral atom determines the physical and chemical characteristics of the element. The periodic table of the elements divides elements into columns based on their characteristics. The number of electrons in a neutral atom, known as the atomic number, Z, is connected to this systematic structure. In this part, we'll see how the exclusion principle is crucial to the underlying theories and how it applies well beyond atomic physics.

Complete Step By Step Answer:
Only hydrogen and helium can have all of their electrons in the n = 1 state according to the Pauli exclusion principle. With three electrons, lithium (see periodic table) must have one in the n = 2 level. As a result, the idea of shells and shell filling emerges. We proceed from hydrogen to helium, lithium, beryllium, boron, and so on as the number of electrons increases, and we find that there are limitations to the number of electrons for each value of n. Because of the different combinations, larger values of the shell n correlate to higher energies and potentially enable more electrons.
a) Using n = 3
The n = 3 field was the final one to be filled in.
We can only complete $18{e^ - }$ since we have to fill 4s first before d after completing $\;1{s^2}\;2{s^2}2{p^6}\;3{p^6}$ . As a result, the correct solution is =18.
However, if we consider that the greatest number of ${e^ - }$ that can be filled in is n=3=2+8+18=28, and that the final e that can fit inside is n=3, the maximum number of ${e^ - }$ will be =30.
$1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}3{d^{10}} = 30$

Note :
Because these electrons are the furthest from the nucleus and hence interact the most with other atoms, the number of electrons in the outermost subshell affects the atom's chemical characteristics. If the outermost subshell can readily receive or give up an electron, the atom will be chemically reactive. The outermost electron configuration of each group in the periodic table defines it. The noble gases, which make up Group 18 (Group VIII), are perhaps the most well-known (helium, neon, argon, etc.).