Sodium ions

Definition and electronic structure

A sodium atom that has lost an electron becomes the monatomic charged sodium ion and is denoted by the symbol Na⁺. Sodium ions have the electronic structure 1s²2s²2p⁶, as they have become oxidised, having lost the lone electron in its 3s subshell: this is why sodium ions have a +1 charge overall.

Sodium ions in the human body
Sodium ions are present in the human body playing key roles in several processes, such as in the primary active transport carried out by the Na⁺/K⁺-ATPase[2], during the depolarisation of neuronal cell membranes during an action potential and as an important component in the secondary active transport of glucose which is completed by the Na⁺-glucose symporter.

In compounds
Sodium ions also form ionic compounds with negative ions, a common example being the neutral ionic compound sodium chloride (NaCl), where the sodium ion has a positive +1 charge (Na⁺) and the chloride ion has a negative -1 charge (Cl^-1).