Potassium

Potassium
Potassium block | Image: Learnool

Potassium (K) is a chemical element of the periodic table, located in group 1 and period 4, having the atomic number 19. It is a soft, silvery white alkali metal whose name comes from the English word “potash”. In nature, potassium only exists in ionic salts. Naturally occurring potassium is made of three isotopes, of which 39K and 41K are stable.

The majority of potassium is found in igneous rocks, shale, and silt in minerals like muscovite and orthoclase feldspar that are insoluble in water. With water, it undergoes a very vigorous reaction that releases hydrogen and produces a potassium hydroxide (KOH) solution. And it produces potassium peroxide (K2O2) when it comes in contact with oxygen.

On periodic table

group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
period
1 1
H
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Hydrogen
2
He
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Helium
2 3
Li
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Lithium
4
Be
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Beryllium
5
B
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Boron
6
C
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Carbon
7
N
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Nitrogen
8
O
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Oxygen
9
F
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Fluorine
10
Ne
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Neon
3 11
Na
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Sodium
12
Mg
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Magnesium
13
Al
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Aluminium
14
Si
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Silicon
15
P
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Phosphorus
16
S
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Sulfur
17
Cl
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Chlorine
18
Ar
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Argon
4 19
K
Potassium
20
Ca
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Calcium
21
Sc
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Scandium
22
Ti
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Titanium
23
V
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Vanadium
24
Cr
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Chromium
25
Mn
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Manganese
26
Fe
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Iron
27
Co
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Cobalt
28
Ni
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Nickel
29
Cu
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Copper
30
Zn
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Zinc
31
Ga
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Gallium
32
Ge
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Germanium
33
As
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Arsenic
34
Se
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Selenium
35
Br
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Bromine
36
Kr
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Krypton
5 37
Rb
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Rubidium
38
Sr
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Strontium
39
Y
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Yttrium
40
Zr
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Zirconium
41
Nb
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Niobium
42
Mo
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Molybdenum
43
Tc
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Technetium
44
Ru
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Ruthenium
45
Rh
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Rhodium
46
Pd
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Palladium
47
Ag
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Silver
48
Cd
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Cadmium
49
In
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Indium
50
Sn
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Tin
51
Sb
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Antimony
52
Te
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Tellurium
53
I
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Iodine
54
Xe
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Xenon
6 55
Cs
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Caesium
56
Ba
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Barium
72
Hf
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Hafnium
73
Ta
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Tantalum
74
W
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Tungsten
75
Re
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Rhenium
76
Os
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Osmium
77
Ir
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Iridium
78
Pt
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Platinum
79
Au
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Gold
80
Hg
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Mercury
81
Tl
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Thallium
82
Pb
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Lead
83
Bi
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Bismuth
84
Po
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Polonium
85
At
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Astatine
86
Rn
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Radon
7 87
Fr
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Francium
88
Ra
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Radium
104
Rf
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Rutherfordium
105
Db
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Dubnium
106
Sg
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Seaborgium
107
Bh
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Bohrium
108
Hs
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Hassium
109
Mt
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Meitnerium
110
Ds
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Darmstadtium
111
Rg
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Roentgenium
112
Cn
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Copernicium
113
Nh
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Nihonium
114
Fl
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Flerovium
115
Mc
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Moscovium
116
Lv
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Livermorium
117
Ts
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Tennessine
118
Og
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Oganesson
57
La
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Lanthanum
58
Ce
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Cerium
59
Pr
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Praseodymium
60
Nd
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Neodymium
61
Pm
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Promethium
62
Sm
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Samarium
63
Eu
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Europium
64
Gd
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Gadolinium
65
Tb
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Terbium
66
Dy
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Dysprosium
67
Ho
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Holmium
68
Er
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Erbium
69
Tm
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Thulium
70
Yb
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Ytterbium
71
Lu
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Lutetium
89
Ac
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Actinium
90
Th
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Thorium
91
Pa
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Protactinium
92
U
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Uranium
93
Np
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Neptunium
94
Pu
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Plutonium
95
Am
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Americium
96
Cm
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Curium
97
Bk
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Berkelium
98
Cf
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Californium
99
Es
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Einsteinium
100
Fm
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Fermium
101
Md
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Mendelevium
102
No
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Nobelium
103
Lr
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Lawrencium
– s block

Potassium is an s-block element, situated in the first column and the fourth row of the periodic table, denoted by the atomic number 19 and chemical symbol K.

Element information

Potassium Element
Potassium appearance | Image: Wikipedia
Potassium Periodic Table
Potassium location on periodic table | Image: Learnool
Potassium is found in the first column of the periodic table below the sodium element.
Origin of name English word “potash”
Symbol K
Atomic number (Z) 19
Atomic mass 39.0983 u
Block s-block
Group 1
Period 4
Classification Alkali metal
Atomic radius 227 pm
Covalent radius 203±12 pm
Van der Waals radius 275 pm
Melting point 63.5 ℃, 146.3 ℉, 336.7 K
Boiling point 757.643 ℃, 1395.757 ℉, 1030.793 K
Electron configuration [Ar] 4s1
Electrons per shell 2, 8, 8, 1
Crystal structure Body-centered cubic (bcc)
Phase at r.t Solid
Density near r.t 0.89 g/cm3
Main isotopes Potassium-39, Potassium-41
Natural occurrence Primordial
Oxidation state +1
Electronegativity (Pauling scale) 0.82
Protons
Neutrons
Electrons
19
20
19
Learn how to find: Potassium protons neutrons electrons
Valence electrons 1
Learn how to find: Potassium valence electrons
CAS number 7440-09-7
Discovered by Humphry Davy in 1807

History

Potassium was first derived from potash, meaning plant ashes, from which it received its name. The English term first appeared in 1648 and is a borrowed translation of the Dutch word potaschen. The chemical symbol K derives from kalium, the Mediaeval Latin for potash, which may have evolved from the Arabic term qali, meaning alkali.[1] Potash and soda (sodium carbonate, Na2CO3) were both referred to as alkali by the Arabs, and there was no distinction between them from antiquity until the Middle Ages. Both substances were known as natron in Europe.

Sir Humphry Davy | Image: Chemistry World

Martin Heinrich Klaproth was the first to differentiate between the two alkalis, suggesting the names kali for vegetable alkali and natron for mineral alkali.[2] Humphry Davy gave the element the name potassium, which he derived from the word potash after he separated the pure element using electrolysis in 1807.

The metals were initially referred to as métal de potasse and métal de soude, and later as Potassium and Sodium by Gay-Lussac and Thénard, who also studied the alkalis. Davy’s research findings were published in German by Ludwig Wilhelm Gilbert. He undoubtedly used Klaproth’s suggestion from 1797.

Gehlen afterwards suggested Kalin(um) and Natrin or Natrinmetall in 1808. Berzelius shortened Potassium and Sodium as Po and So in 1813. Despite a list of names in many languages, Gilbert and Klaproth’s names Natrium and Kalium were eventually chosen by Germanic countries, while Davy and Gay-Lussac/Thénard’s names Sodium and Potassium were accepted by English and French-speaking countries.

Occurrence

About 2.6 Percent Of The Mass Of Earth's Crust Is Potassium
About 2.6 percent of the mass of Earth’s crust is potassium | Image: The Layered Earth

Potassium is not found in its elemental form in nature because it reacts so easily with water. Because of this, the majority of potassium is found in the Earth’s crust as clays and feldspars. It is the seventh most abundant element in the Earth’s crust, making up around 2.6% of its weight. Numerous additional saline bodies of water are rich in potassium, with the Dead Sea having an estimated potassium chloride level of 1.7%. All fruits, vegetables, meat, and fish contain potassium. Potassium is abundant in leafy greens, beans, nuts, dairy products, milk, chocolate, bananas, and avocados.

Production

Most commercial potassium compounds are produced by electrolysis from soluble potassium compounds, such as carnallite, sylvite, polyhalite, and langbeinite, which are discovered in old lakes and seabeds. In 2021, it was predicted that the world would produce about 71.9 million tonnes of potash. Canada is the world’s largest potash producer, accounting for 31% of world production in 2021.[3] About 70% of the potash produced worldwide in 2021 was produced by three nations Belarus, Russia, and Canada.

Metallic potassium and sodium-potassium alloys (NaK) are produced by reacting high temperature sodium at atmospheric pressure with molten potassium chloride.[4]

Na + KCl → NaCl + K

An equilibrium vapor of sodium and potassium is produced when molten potassium chloride is added to a tightly packed column and brought into contact with rising sodium vapors in a reaction zone. The lighter boiling potassium is separated to the required degree of purity using a fractionating column located above the reaction zone. The generated sodium chloride is continually removed from beneath the reaction zone.

Properties

When Cut, Potassium's Silvery Color Changes To Gray
When cut, potassium’s silvery color changes to gray | Image: Science Stock Footage

Potassium is easily sliced with a knife. It is silvery when first cut, but as soon as it comes into contact with oxygen, it starts to tarnish and turn gray.

It is one of the alkali metals in the periodic table that possesses a single valence electron in the outer electron shell.

It has a low melting point and is a good conductor of heat and electricity.

Pure potassium is a highly reactive metal that explodes with a purple flame when it comes in contact with water. Hence for safety reasons, this metal is typically stored under mineral oil.

Applications

Fertilizers use potassium. It plays a significant role in boosting crop yields and overall crop quality, as well as strengthening plants’ defenses against disease.

It is combined with sodium to form an alloy that acts as a liquid metallic heat-transfer medium.

Potassium is used as a bleaching agent in the textile industry and also used in the tanning of leather.

Potassium is used as a flavor enhancer in food, and it is also used as a preservative to prevent food from spoiling.

Potassium is used as a medication to prevent or treat hypokalemia (low blood levels of potassium).

Potassium is used as an oxidizing agent in gunpowder. Also used in explosives, fireworks, and matches.

Potassium is used in color TV tubes and fluorescent lamps. It is used as a drying agent in laboratories. And is used in the manufacture of glass, liquid soap, and detergent.

Many different kinds of magnetometers utilize metallic potassium.

Interesting facts

Potassium is the seventh most abundant element in the human body.

Potassium was the first metal discovered by electrolysis.

Potassium is less dense than water, so it floats on water.

Potassium Burns With A Lilac-Colored Flame
Potassium burns with a lilac-colored flame | Image: Fine Art America

Potassium produces a violet or light purple flame, popularly known as a lilac flame.

Potassium is the second least dense metal after lithium.

Related

More elements

s block
p block
d block
f block
Barium Aluminium Bohrium Actinium
Beryllium Antimony Cadmium Americium
Caesium Argon Chromium Berkelium
Calcium Arsenic Cobalt Californium
Francium Astatine Copernicium Cerium
Helium Bismuth Copper Curium
Hydrogen Boron Darmstadtium Dysprosium
Lithium Bromine Dubnium Einsteinium
Magnesium Carbon Gold Erbium
Potassium Chlorine Hafnium Europium
Radium Flerovium Hassium Fermium
Rubidium Fluorine Iridium Gadolinium
Sodium Gallium Iron Holmium
Strontium Germanium Lawrencium Lanthanum
Indium Lutetium Mendelevium
Iodine Manganese Neodymium
Krypton Meitnerium Neptunium
Lead Mercury Nobelium
Livermorium Molybdenum Plutonium
Moscovium Nickel Praseodymium
Neon Niobium Promethium
Nihonium Osmium Protactinium
Nitrogen Palladium Samarium
Oganesson Platinum Terbium
Oxygen Rhenium Thorium
Phosphorus Rhodium Thulium
Polonium Roentgenium Uranium
Radon Ruthenium Ytterbium
Selenium Rutherfordium
Silicon Scandium
Sulfur Seaborgium
Tellurium Silver
Tennessine Tantalum
Thallium Technetium
Tin Titanium
Xenon Tungsten
Vanadium
Yttrium
Zinc
Zirconium

References

1. Atomic Weight of Potassium – CIAAW

2. Kalium (Potassium) – Elementymology & Elements Multidict

3. Potash facts

4. The Manufacture of Potassium and NaK – ACS Publications

External links

Deep

Learnool.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.

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