{"id":26,"date":"2020-04-08T14:56:44","date_gmt":"2020-04-08T14:56:44","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=26"},"modified":"2023-08-16T11:06:19","modified_gmt":"2023-08-16T11:06:19","slug":"potassium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/potassium\/","title":{"rendered":"Potassium (K)"},"content":{"rendered":"\n

\"\"<\/h3>\n\n\n\n

Potassium is a chemical element with the atomic number 19 in the periodic table of elements. With about 2.0 to 2.5 percent occurrence in the Earth\u2019s crust, it\u2019s the eighth most abundant element found in the layers of our planet. As a member of the alkali metals family in the periodic table<\/a>, potassium has one valence electron in its outermost shell. <\/span><\/p>\n\n\n\n

This extremely reactive chemical is also one of the most essential trace minerals found in the human body, and it\u2019s responsible for some vital processes. Most notably, it\u2019s responsible for the control and regulation of the exchange of electrical impulses in the heart\u2019s cells and within other muscles, as well as the regulation of the fluid balance within the body.<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

Chemical and Physical Properties of Potassium<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>K<\/td><\/tr>
Name<\/td>Potassium<\/td><\/tr>
Atomic number<\/td>19<\/td><\/tr>
Atomic weight (mass)<\/td>39.0983 g.mol-1<\/td><\/tr>
Uses<\/td>Used as potash in making glass & soap. Also as saltpeter, potassium nitrate (KNO3) to make explosives and to color fireworks in mauve. Formerly called kalium (K). Vital to function of nerve and muscle tissues.<\/td><\/tr>
Description<\/td>Fairly hard, silvery-white metal. Fifth most abundant element in the earth’s crust (41,500 ppm). Occurs only in compounds.<\/td><\/tr>
Group<\/td>1 (Alkali Metals<\/a>)<\/td><\/tr>
Period<\/td>4<\/td><\/tr>
Color<\/td>Silvery-white<\/td><\/tr>
Physical state<\/td>A soft metal at room temperature<\/td><\/tr>
Half-life<\/td>From less than 10 picoseconds to 1.248\u00d7109 years<\/td><\/tr>
Electronegativity<\/td>0.82<\/td><\/tr>
Density<\/td>0.862 g.cm-3<\/td><\/tr>
Melting point<\/td>336.9\u00b0C<\/td><\/tr>
Boiling point<\/td>1038.7\u00b0C<\/td><\/tr>
Van der Waals radius<\/td>0.235 nm<\/td><\/tr>
Ionic radius<\/td>1.51 (+1) \u00c5<\/td><\/tr>
Isotopes<\/td>26<\/td><\/tr>
Most characteristic isotope<\/td>39K<\/td><\/tr>
Electronic shell<\/td>[Ar] 4s1<\/td><\/tr>
The energy of the first ionization<\/td>418.6 kj.mol-1<\/td><\/tr>
Covalent Radius<\/td>2.03 \u00c5<\/td><\/tr>
Atomic Radius<\/td>2.77 \u00c5<\/td><\/tr>
Atomic Volume<\/td>45.46 cm\u00b3\/mol<\/td><\/tr>
Name Origin<\/td>English: pot ash; symbol from Latin: kalium, (alkali).<\/td><\/tr>
Discovery date<\/td>In 1807 by Sir Humphrey Davy<\/td><\/tr>
Location<\/td>England<\/td><\/tr>
Pronunciation<\/td>pe-TASS-i-em<\/td><\/tr>
Oxidation States<\/td>1<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Represented by the symbol K, the chemical element potassium has the atomic number 19, an atomic mass of 39.0983 g.mol<\/span>-1<\/span>, and electron configuration [Ar] 4s<\/span>1<\/span>. Potassium is a soft, silvery-white metal that reaches its boiling point at 759\u00b0C (1398\u00b0F or 1032 K), while the melting point is achieved at 63.5\u00b0C (146.3\u00b0F or 336.7 K). <\/span><\/p>\n\n\n\n

This alkali element of the periodic table has an electronegativity of 0.8 according to Pauling, whereas the atomic radius according to van der Waals is 0.235 nm. <\/span><\/p>\n\n\n\n

As it has a lower density than water, potassium can actually float on it. However, when it comes into contact with H2O (water) molecules, this soft metal reacts violently by releasing hydrogen<\/a> and emitting a purple flame. In contact with air, the elemental potassium oxidizes and tarnishes very quickly.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

How Was Potassium Discovered?<\/span><\/h2>\n\n\n\n

Since 500 A.D., people would collect the ashes from burnt wood and wash them in order to obtain <\/span>potash, <\/span><\/i>also referred to as<\/span> vegetable alkali<\/span><\/i>. This is a potassium compound called potassium carbonate (K2 CO3), which was used as a cleaning agent. At the time, people were also familiar with another similar substance that they obtained from a specific type of rock with mineral alkali properties. They called it <\/span>soda ash (<\/span><\/i>sodium carbonate, Na2 CO3). The two substances differed only based on the source they were obtained from.\u00a0<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

Contributions by Sir Humphry Davy<\/span><\/h3>\n\n\n\n

In 1806, the English chemist Sir Humphry Davy attempted to distinguish these two substances by isolating the compounding elements. To that end, Davy attempted electrolysis on both compounds. However, due to the high reactivity of potassium and sodium, the first experiment of the English chemist left no significant results. Namely, although the electric current indeed freed potassium and sodium<\/a> from the compound, they instantly reacted with the H<\/span>2<\/span>O (water) molecules.<\/span><\/p>\n\n\n\n

Luckily, this didn\u2019t discourage Davy. During his second attempt to separate the elements from the potash and soda ash compounds, he decided to leave out the water. This time, he passed the electric current through molten samples of both compounds, which resulted in a metal droplet formed by each substance – a pure elemental form of potassium that was isolated from the potash and a pure sodium metal was isolated from the soda ash.<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

How Did Potassium Get Its Name?<\/span><\/h2>\n\n\n\n

Sir Humphrey Davy kept the old English name for the newly discovered element, calling it \u2018<\/span>potash<\/span><\/i>\u2019, which is short for \u2018pot of ash\u2019 – the method previously used to obtain this chemical.<\/span><\/p>\n\n\n\n

The chemical symbol of potassium (K) represents the initial letter of <\/span>kalium – <\/span><\/i>the Medieval Latin word for <\/span>potash<\/span><\/i>. A deeper etymological analysis of this term leads to the Arabic word \u2018<\/span>quali\u2019<\/span><\/i> that means <\/span>alkali<\/span><\/i>, i.e. a soluble salt.<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

Where Can You Find Potassium?<\/span><\/h2>\n\n\n\n

Potassium cannot be found freely in nature. It mostly occurs as a part of mineral formations, such as clay or feldspar. With the weathering of these rock-forming tectosilicate minerals, potassium finds its way to surface waters. Thus, the average potassium concentration in the sea amounts to 0.75 grams per liter. <\/span><\/p>\n\n\n\n

For commercial purposes, this alkali metal is most often obtained by mining the minerals alunite, carnallite, langbeinite, polyhalite, and sylvite. The largest potassium mines in the world are located in the United States, Germany, Canada, New Mexico, Utah, and Chile.  <\/span><\/p>\n\n\n\n

Element 19 is also found in almost all plants and animals, as well as inside the human body. Since it reacts strongly with water, potassium is one of the most important minerals that support various biological functions in living organisms.<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

Potassium in Everyday Life<\/span><\/h2>\n\n\n\n

Although the pure, elemental form of potassium has limited use in everyday life, the various compounds of this chemical element have numerous applications. Especially notable are the uses of potassium chloride, potassium sulfate, and potassium nitrate. These compounds have been extensively used in agriculture as soil fertilizers.<\/span><\/p>\n\n\n\n

<\/div>\n\n\n\n

Potassium and Health<\/span><\/h2>\n\n\n\n

The most vital role of this alkali is in the biological processes of living organisms, especially humans. According to the <\/span>American Heart Association<\/span><\/a>, potassium is responsible for lowering blood pressure, maintaining a balanced water level, muscle contractions, activation of nerve impulses, brain and heart function, reflexes, maintaining the brain-blood supply system, etc. <\/span><\/p>\n\n\n\n

Moreover, potassium is considered to be a nutrient of public health concern by the <\/span>United States Department of Agriculture (USDA)<\/span><\/a>, as failing to consume sufficient levels of the nutrient can increase the risk of stroke, hypertension, heart failure, and other types of cardiac diseases.<\/span><\/p>\n\n\n\n

Potassium-Rich Foods<\/span><\/h4>\n\n\n\n

Since it\u2019s not normally produced in the body, the daily intake of foods that contain a high level of potassium is strongly recommended. Some great sources of potassium include:<\/span><\/p>\n\n\n\n