Why are Sodium and Chlorine not stable elements?

Answer 1

Sodium and Chlorine are chemically unstable due to the amount of electrons each has in the outer shells (also known as layers) of their atoms.

Sodium has 11 electrons.

First shell: 2 electrons

Second shell: 8 electrons

Third shell: 1 electron

As the number of electrons in the last shell is not 8 and as the shell is not full Sodium is chemically unstable.

Chlorine has 17 electrons. They are arranged like this:

First shell: 2 electrons

Second shell: 8 electrons

Third shell: 7 electrons

The number of electrons in the last shell is not 8, and the shell is not full, and thus, chlorine is chemically unstable.

To give an example of a chemically stable element, Argon has 8 atoms in its last shell, which is why it is chemically stable and therefore does not react with any element.

Answer 2

Sodium and chlorine are not stable elements on their own because they are highly reactive. Sodium readily loses an electron, while chlorine readily gains an electron to achieve a stable electron configuration, which usually involves forming ionic bonds with other elements to become stable.