Potassium is an interesting metal like sodium. Both sodium and potassium are toxic to humans in the metallic form. However, both are essential for homeostasis in the ionic form. Potassium ions are as important as sodium ions in maintaining the resting electric potential across the cellular membrane. Potassium being more important than sodium.
Potassium ions are found predominantly inside the cell, while very low concentrations of it are found outside the cell. This is in contrast to sodium which is found predominantly outside the cell, while a very low concentration of sodium is found inside the cell. The driving force for this high energy process is driven by enzymes that are called ATPase.
Potassium channel blockers are used clinically in order to induce a state of continuous neurons firing and continuous muscle contraction.
Potassium is located below sodium in the periodic table. It is more reactive than sodium. Potassium has a similar outer electronic configuration as sodium. It has the electronic configuration of argon with an additional 4s orbital electron. 4s electron being more diffuse and energetically higher than the 3s orbital electron of sodium. The additional 4s electron in potassium makes it extremely electropositive.
It gives this electron easily and exothermically to any electron acceptor such as lewis acids.
Potassium like all alkali metals crystallizes in a body centered cubic crystal. It has a low melting point.
Potassium has many important compounds such as KO2 which is used in breathing machines. Another compound of potassium is KNO3. It is a strong oxidizing compound that is used in gunpowder and pyrotechnics. This is also in addition to its use as a fertilizer. KClO3 is another compound of potassium that is used in the matches industry.
One of the many compounds of potassium is KCl. This compound is used pharmaceutically as a substitute to eating salt (NaCl) in patients with hypertension. Sodium is known to induce hypertension so KCl gives the taste of eating salt without triggering hypertension.
Potassium can be used in all the reactions of sodium, except that all its reactions are more exothermic. It can be used in ammonia solutions to generate solvated electrons. These solvated electrons are excellent reducers. They can be used in the Birch reduction of benzene. It can also be used to reduce triple bonds to double bonds. The reduction of triple bonds with solvated electrons differs from the reduction with molecular hydrogen in that the solvated electrons generate trans alkenes while the hydrogen reduction gives cis alkene.
Potassium reacts vigorously with water to give potassium oxide and hydrogen according to the following equation:
K + H2O-> K2O + H2
Due to the large size of potassium ions, it is not easily solvated in organic solvents. Therefore methods have been developed to solvate potassium ions. These methods include crown ether’s with varying number of oxygen atoms. These crown ether’s are capable of dissolving potassium ions as well as other alkali metal ions.
Potassium as well as other alkali metals reacts with alkyl halides to generate alkyl potassium. The difference between the starting material and the product being an electrophile was converted into a nucleophile ( the alkyl potassium).
Potassium is a soft metal and has the electronic configuration of argon with an additional electron in the 4s orbital. The ionization energy of the 4s electron of potassium is lower than that of the 3s electron of sodium. This is so due to the higher energy of the 4s electron. Its melting point is 63.7 degrees Celsius which is lower than that of sodium. Its density is also lower than that of sodium.
Its boiling point is 759 degrees Celsius which is lower than that of sodium. Its density is lower than that of sodium. Potassium ionic diameter is 276 pm which is comparable to that of barium which has an ionic diameter of 270 pm. Therefore one would expect a similar chemistry between these two ions. The atom that is diagonally equivalent to potassium is strontium. Potassium reacts vigorously and exothermically with the halogens and the chalcogens.