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Minerals in Detail
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
POTASSIUM
Potassium - chemical details
| Symbol | K |
| Atomic number | 19 |
| Atomic mass | 39.0983 g.mol-1 |
| Electronegativity | 0.8 (according to Pauling) |
| Density | 0.86 g.cm-3 at 0 °C |
| Melting point | 63.2 °C |
| Boiling point | 760 °C |
| Vanderwaals radius | 0.235 nm |
| Ionic radius | 0.133 (+1) |
| Isotopes | 5 |
| Electronic configuration | [ Ar ] 4s1 |
| Energy of first ionisation | 418.6 kJ.mol-1 |
| Energy of second ionisation | 3052 kJ·mol-1 |
| Energy of third ionisation | 4420 kJ·mol-1 |
| Standard potential | -2.931 |
| Discovered | 1808 - Sir Humphry Davy |
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Potassium - Description
The name is derived from the English word potash. The chemical symbol K comes from kalium, the Mediaeval Latin for potash, which may have derived from the
Arabic word qali, meaning alkali.
Potassium, a member of the alkali group of the periodic chart, is a soft, silvery-white metal when first cut but it oxidizes rapidly in air and tarnishes
within minutes, so it is generally stored under oil or grease. It is light enough to float on water with which it reacts instantly to release hydrogen,
which burns with a lilac flame.
The chemistry of potassium is almost entirely that of the potassium ion, K+.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Potassium - Industrial applications
By far the biggest industrial use is in fertiliser. The remainder goes into television manufacture, pharmaceuticals, baking and tanning. For details on
industrial applications and impact on the environment see www.lenntech.com/Periodic-chart-elements/K-en.htm
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Potassium - In natural form
Most potassium occurs in the Earth's crust as minerals, such as feldspars and clays. Potassium is leached from the soil by weathering, which explains why
there is quite a lot of this element in the sea (0.75 g/liter). Minerals mined for their potassium are sylvite, carnallite and alunite. The main mining area
used to be Germany, which had a Potassium monopoly before the First World War. Today most potassium minerals come from Canada, the USA and Chile. The world
production of potassium ores is about 50 million tonnes, and reserves are vast (more than 10 billion tonnes).
Potassium is a key plant element. Although it is soluble in water, little is lost from undisturbed soils because as it is released from dead plants and
animal excrements, it quickly becomes strongly bound to clay particles, and it is retained ready to be re-absorbed by the roots of other plants.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Potassium - Impact on health
Potassium can be found in vegetables, fruit, potatoes, meat, bread, milk and nuts.
It plays an important role in the physical fluid system of humans and it assists nerve functions. Potassium, as the ion K+, concentrates inside cells, and
95% of the body's potassium is to be found in the cells. When kidneys are somehow malfunctioning an accumulation of potassium will occur. This can disturb
heart rhythm.
Potassium cations are important in neuron (brain and nerve) function, and in influencing osmotic balance between cells and the interstitial fluid.1
Potassium is also important in allowing muscle contraction and the sending of all nerve impulses in animals through action potentials. By nature of their
electrostatic and chemical properties, K+ ions are larger than Na+ ions, and ion channels and pumps in cell membranes can distinguish between the two types
of ions, actively pumping or passively allowing one of the two ions to pass, while blocking the other.2
References:
- Campbell, N. (1987). Biology, Benjamin Cummins:NY. P. 795.
- Lockless, S., Zhou, M., & MacKinnon, R. (). Structural and thermodynamic properties of selective ion binding in a K+ channel. PLos Biol. 2007 May; 5(5): e121. http://www.ncbi.nlm.nih.gov/pubmed/17472437. Retrieved 24 Sep 2008.
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