how does it react chemically?
It is chemically very similar to sodium.
Potassium
Potassium is chemically very similar to sodium, the previous element in group 1 of the periodic table.
where is potassium located in the human body cells
wiki:25673303
Potassium [SEP] Introduction
Potassium in nature occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-colored flame. It is found dissolved in sea water (which is 0.04% potassium by weight), and occurs in many minerals such as orthoclase, a common constituent of granites and other igneous rocks. Potassium is chemically very similar to sodium, the previous element in group 1 of the periodic table. They have a similar first ionization energy, which allows for each atom to give up its sole outer electron. It was suspected in 1702 that they were distinct elements that combine with the same anions to make similar salts, and was proven in 1807 using electrolysis.