Question

What is the ground-state electron configuration of a neutral atom of sodium?

Answer 1

We know that for a neutral atom, the atomic number is just equal to the number of electrons. As we start to write the electron configuration for sodium, we should be aware of how many electrons it has. Atomic number informs us about the number of electrons a neutral atom has and by using Pauli’s exclusion principle, Hund’s rule of maximum multiplicity, Aufbau Principle to fill the electron.

Complete answer: To know the atomic number we simply need to have a look in the periodic table. For a neutral atom, the atomic number is just equal to the number of electrons. This is due to the atomic number depending on the number of protons it has. As that neutral means a charge of zero, so to acquire a zero charge, the positively charged particles that are protons must be equal to the negatively charged particle which is electrons.
Aufbau’s principle states that in the ground state of atoms, the orbitals are filled in order of their increasing strength. Pauli’s exclusion law states that only two electrons can be there in an orbital having opposite spins. And Hund’s rule state that pairing of electron does not takes place until each orbital belonging to that shell has got one electron each so according to these rules the electronic configuration of sodium will be as follows: $[Na]=1{{s}^{2}},2{{s}^{2}}2{{p}^{6}},3{{s}^{1}}$

Note:
Remember that firstly we need to check the periodic table for checking the electrons titanium has and then need to write electronic configuration based on that. Electronic configuration should be written by following all the rules.