Question

What is the difference between $Na$ and $N{a^ + }$ in terms of the number of electrons?

Answer 1

There is a difference between atoms and ions that we need to know. Ions are the charged species while atoms are uncharged species. Atoms are neutral; they don’t have any charge like sodium atom $Na$ while ions like $N{a^ + }$ have a positive charge. It can be negative for other elements.

Complete answer:
As we know the atomic number of sodium $(Na)$ is $11$, since atoms are neutral, we know that the sodium atom must also have $11$ electrons and $11$ protons. All electrons are arranged into energy levels. These energy levels hold a certain number of electrons.
As sodium has eleven electrons. The first two fill the outermost energy level. The second energy level is also full, holding eight electrons and one electron remaining in the outer energy level. The electronic configuration of sodium atom $(Na)$ is $1{s^2}2{s^2}2{p^6}3{s^1}$. Because of this one electrons sodium atom is unstable, so to achieve the noble gas configuration and to get stable sodium atom donate one electron to the other metal forming $N{a^ + }$ ion the electronic configuration become $1{s^2}2{s^2}2{p^6}$ and the total electron will be $10$.
The total number of electrons is $10$ in the case of $N{a^ + }$ and $11$ in the case of $Na$, while the number of protons is the same, i.e. eleven in both cases. Cations of a given metal have a smaller radius than the neutral atom so that $N{a^ + }$ will decrease in size compared with the sodium atom.
Reaction of sodium atoms and the reaction of sodium ions with water are different. We know that sodium atoms react with water vigorously while sodium ions do not react with water at all.

Note:
Remember the atom and ions are different. They differ in their chemical properties due to differences in the number of electrons. But protons are the same in both cases, the sodium atom is neutral while the sodium ion is positively charged, the sodium atom is poisonous while the sodium ion is non-poisonous.