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Potassium is an element of great importance for different reasons. To begin with, it is an essential mineral for the proper functioning of the human body, as well as the cells of most living beings. In addition, it has characteristics and chemical properties that make it a very reactive metallic element . With that being said, here are the most important facts about this item:
Summary of the most important chemical properties
| Name: | Potassium |
| chemical symbol: | k |
| Atomic number (Z): | 19 |
| Average Atomic Weight: | 39.0983(1) |
| Electronic configuration: | 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 |
| Valence Electrons: | 1 |
| Period: | 4th |
| Cluster: | 1 (formerly called 1A) |
| Block of the periodic table: | S |
| Item Type: | alkali metal |
Physical properties of potassium
The following table presents the data related to the most important physical properties of this element.
| Density at 20 °C: | 0.862 g/ cm3 |
| Melting point: | 63°C |
| Fusion enthalpy: | 2.4 kJ/mol |
| Boiling point: | 760°C |
| Vaporization enthalpy: | 79.1 kJ/mol |
| Atomization enthalpy: | 90.14kJ/mol |
| Atomic radio: | 235 p.m. |
| Ionic radius of the ion K + : | 133 p.m. |
| 1st ionization energy: | 418.81 kJ/mol |
| 2nd ionization energy: | 3051.85kJ/mol |
| 3rd ionization energy: | 4419.64 kJ/mol |
| Pauling Electronegativity: | 0.8 |
| Standard reduction potential: | K + + e – → K E°=-2.93 V |
| Electrical resistance at 20 °C: | 6.15 µΩcm |
As you can see, potassium is a light, solid metal that floats on water and melts easily due to its relatively low melting point. It is a highly reactive metal that serves as a reducing agent thanks to a considerably negative reduction potential.
Additional Facts and Fun Facts About Potassium
1. Potassium metal is soluble in ammonia.
A peculiarity of potassium and some other active metals is that it is soluble in liquid ammonia. In these cases an oxidation process occurs in which the electron is solvated, producing a beautiful blue colored solution.
2. Slowly reacting with an excess of oxygen forms potassium peroxide.
Peroxides are ionic compounds in which the peroxide ion (O 2 2- ) and a cation of an active metal are present. Under mild reaction conditions and an excess of oxygen, potassium reacts according to the following equation to form potassium peroxide:
Peroxides such as potassium peroxide react with water to form alkaline solutions of hydrogen peroxide.
3. When burned in air, potassium forms a superoxide.
Potassium peroxide is not the only important chemical species that is formed by the reaction between potassium and oxygen. In fact, potassium can burn in air to form a particularly reactive ion called superoxide (O 2 – ) in which oxygen is considered to have an oxidation state of -1/2. The reaction is:
4. The crystal structure of metallic potassium is cubic, centered on the body.
This metal has a cubic structure with an edge of 533.4 pm and belongs to the space group Im3m.
5. Its chemical symbol comes from the word kalium .
The chemical symbol K comes from kalium , which is the Latin name for potassium. This name, in turn, comes from the Arabic word for alkaline.
6. It has three stable isotopes.
The three natural isotopes of potassium are K-39, K-40 and K-41. The atomic masses of each isotope and their respective abundances are:
| Isotope | Atomic mass (amu) | Isotopic abundance (%) |
| K-39 | 38.9637068(3) | 93.2581(44) |
| K-40 | 39.9639987(3) | 0.0117(1) |
| K-41 | 40.9618260(3) | 6.7302(44) |
7. It is the seventh most abundant element in the earth’s crust.
Potassium represents 2.41% of the mass of the earth’s crust, which makes it the seventh most abundant element, after oxygen, silicon, aluminum, iron, calcium and sodium.
8. It is the sixth most abundant element in seawater.
On average, the sea contains about 1,800,000 tons of dissolved potassium for every cubic mile of water. This makes it the sixth most abundant element in the ocean, but the fourth if we don’t count the hydrogen and oxygen that make up water.
9. It is an essential mineral for life.
Potassium fulfills an endless number of functions at a biological level. On the one hand, it is essential for nerve conduction, which is why it is an essential part of the nervous system. In addition, it is also involved in the process of muscle contraction.
Potassium is also one of the ions that contributes to maintaining the electrical potential of the cell membrane. It is involved in the process of repolarization of the membrane after firing the action potential in neurons. In addition, potassium is also involved in the processes that cells use to capture nutrients from the extracellular space and to eliminate the waste produced during their metabolism.
10. It was the first metal to be isolated and purified by electrolysis.
This element was obtained in its pure metallic form for the first time in 1807 thanks to the work of Humphry Davy. This chemist managed to obtain this metal by electrolysis of potassium hydroxide (KOH).
11. Burn in the flame with a lilac or violet color.
Potassium emits a lilac or purple color when compounds containing it are burned in a flame. This is a fairly simple test to confirm the presence of this alkali metal in a sample.
12. It is abundant in many foods
Many natural foods contain significant amounts of potassium. Among the most important are:
| Fruit | Bananas or plantains, papaya, raisins and also plums, mangoes and oranges, among others. |
| Vegetables | Potato, sweet potato, mushrooms, tomatoes, Brussels sprouts, zucchini, avocado and broccoli, among others. |
| proteins | Beans, soybeans or soybeans, salmon, turkey meat, peanut butter, lean beef and sunflower seeds, among others. |
References
- educaplus.org. (n.d.). Element properties . http://www.educaplus.org/elementos-quimicos/propiedades/abun-geo-tierra.html
- Generalic, E. (2021, January 22). Potassium . enig. Periodic table of elements. KTF-Split. https://www.periodni.com/es/k.html
- List Of Foods With Potassium Content . (2021, September 8). Drugs.com. https://www.drugs.com/cg_esp/lista-de-alimentos-con-contenido-de-potasio.html
- May, P. (1909, July). The use of liquid ammonia as a solvent . JSTOR. https://www.jstor.org/stable/43769134
- Potassium in the diet . (2020, March 19). Medlineplus.gov. https://medlineplus.gov/spanish/potassium.html
- XI. The chemical composition of seawater . (n.d.). Biblioteca digital.Ilce.Edu. Retrieved October 1, 2021, from http://bibliotecadigital.ilce.edu.mx/sites/ciencia/volumen1/ciencia2/12/htm/sec_16.html
