Potassium ions

Potassium ions are important in many biological processes. These are atoms of potassium, an alkaline metal, with an atomic number of 19 and symbol of K, that have lost their highest energy electrons to form a full outer shell. This gives them an electron configuration of  1s2 2s2 2p6 3s2 3p6, and a charge of plus one, donated by K⁺. 

In biological systems potassium is the most abundant cation in theextracellular fluid of animals. The electrochemical gradient between the inside and outside of the cell helps to maintain the membrane potential of the cell. Potassium ions are driven to out of the cell by this gradient, but the appropriate concentration of K⁺ is maintained by the sodium potassium pump which pumps in 2 K⁺ ions for every 3 Na⁺ ions it pumps out.