Potassium
Potassium General
| Name:Potassium | Symbol:K |
| Type:Alkali Metal | Atomic weight:39.0983 |
| Density @ 293 K:0.862 g/cm3 | Atomic volume:45.46 cm3/mol |
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Discovered:
Sir Humphry Davy discovered potassium in 1807 by the electrolysis of potassium hydroxide (potash). The metal collected at the cathode. This was the first metal isolated by electrolysis. The name potassium is from the English word 'potash', originally meaning an alkali extracted with water in a pot of ash of burnt wood or tree leaves. |
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Potassium States
| State (s, l, g):solid | |
| Melting point:336.5 K (63.4 °C) | Boiling point:1038.7 K (765.6 °C) |
Potassium Energies
| Specific heat capacity:0.75 J g-1 K-1 | Heat of atomization:89 kJ mol-1 |
| Heat of fusion:2.334 kJ mol-1 | Heat of vaporization :79.870 kJ mol-1 |
| 1st ionization energy:418.8 kJ mol-1 | 2nd ionization energy:3051.3 kJ mol-1 |
| 3rd ionization energy:4411.3 kJ mol-1 | Electron affinity:48.385 kJ mol-1 |
Potassium Oxidation & Electrons
| Shells:2,8,8,1 | Electron configuration: [Ar] 4s1 |
| Minimum oxidation number: 0 | Maximum oxidation number:1 |
| Min. common oxidation no.: 0 | Max. common oxidation no.:1 |
| Electronegativity (Pauling Scale):0.82 | Polarizability volume:43.4 Å3 |
Potassium Appearance & Characteristics
| Structure:bcc: body-centered cubic | Color:silvery-white |
| Hardness:0.4 mohs | |
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Harmful effects:
Potassium is considered to be non-toxic. Due to its highly reactive nature, elemental potassium must be handled with extreme care. |
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Characteristics:
Potassium is silvery-white, low melting, metal soft enough to be easily cut with a knife. It tarnishes rapidly in air, forming a dull oxide coating. Potassium burns with a lilac colored flame. It is extremely reactive, reacting violently with water, for example, to produce hydrogen gas and potassium hydroxide. Uses: Potassium is vital for plant growth. Plants use it, for example, to make proteins, hence the greatest demand for potassium compounds is in fertilizers. Potassium hydroxide is a strong alkali and an important industrial chemical. It is used in the manufacture of soft soaps and as an electrolyte in alkaline batteries. Potassium chloride is used as a healthier alternative to table salt. Toughened glass can be made by immersing glass in molten potassium nitrate. Potassium nitrate is the main explosive ingredient in gunpowder. |
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Potassium Reactions
| Reaction with air:vigorous, ⇒ KO2 | Reaction with 6 M HCl:vigorous, ⇒ H2, KCl |
| Reaction with 15 M HNO3:vigorous, ⇒ H2, NOx, KNO3 | Reaction with 6 M NaOH:vigorous, ⇒ H2, KOH |
Potassium Compounds
| Oxide(s): K2O | Chloride(s):KCl |
| Hydride(s): KH |
Potassium Radius
| Atomic radius:220 pm | Ionic radius (1+ ion):152 pm |
| Ionic radius (2+ ion):pm | Ionic radius (3+ ion):pm |
| Ionic radius (2- ion):pm | Ionic radius (1- ion):pm |
Potassium Conductivity
| Thermal conductivity:102.5 W m-1 K-1 | Electrical conductivity:0.164 x 106 S cm-1 |
Potassium Abundance & Isotopes
| Abundance earth's crust:2.1 % by weight, 1.6 % by moles | |
| Abundance solar system:4 parts per million by weight, 100 parts per billion by moles | |
| Cost, pure:$100 per 100g | |
| Cost, bulk:$65 per 100g | |
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Source:
Potassium does not occur as a free element in nature; it is too reactive, forming compounds from which it is difficult to separate. Potassium is obtained commercially by electrolysis of potassium hydroxide or potassium chloride |
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Isotopes:
Potassium has 20 isotopes whose half-lives are known, with mass numbers 35 to 54. Of these, two are stable, 39K, and 41K. Over 93.2% of naturally occurring potassium is in the form of 39K. |
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Potassium Other
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Other:
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