Potassium
Brittany Warren
December 16, 2010
In the world, pure substances are used in everyday life as we know it. Over the years
scientists have called these pure substances elements. These elements have many different
characteristics, looks, uses, chemical properties, masses, and symbols. One of these elements
is the potassium element. Potassium gets its specific name from the combination of its
historical background, specific characteristics, chemical properties, and other interesting
facts.
Potassium in its purest form is a silvery-white metal. It is so soft that it can be cut with
a knife. On the periodic table of elements it is located right below the sodium element. Since
it is located so close to sodium this means that sodium and potassium are very close
chemically and are each just as abundant in nature as the other. But it is never actually found
in nature by itself. Potassium forms a 1+ ion. It is in the alkali metal group, also known as
Group 1 or 1A. (Baker) This group consists of lithium, sodium, rubidium, cesium and
francium. “Many potassium salts are of utmost importance, including the hydroxide, nitrate,
carbonate, chloride, chlorate, bromide, iodide, cyanide, sulfate, chromate, and dichromate”
(Lide).
Potassium originates from potash and its symbol - K - comes from the Latin word
kalium (Potassium, historical information). In 1807, Sir Humphrey Davy discovered
potassium. It was obtained from wood ash by boiling it and therefore reducing it to
powder. Potash, a compound of potassium and a vegetable alkali, is produced when wood
burns. Ashes of wood were washed with water to dissolve the potash. Its atomic number is
19 and the true atomic mass is 39.0983 amu. Like stated before, potassium is classified in the
group IA, which are Alkali metals (Baker). Potassium's melting point is 63° Celsius (145°
Fahrenheit) and a boiling point of 770° Celsius (1,420° F). The melting point is equal to that
of a candle flame (Baker).
Potassium makes up 1.5% by weight of Earth's crust and is essential to all living
things. Potassium is found in plants, rocks and in the sea (Knapp). Seawater holds the largest
amount of potassium. There is nearly half a kilogram of potassium oxide in each cubic meter
of seawater (Knapp). Desert lakes, ancient desert rocks, and volcanic rocks are also excellent
places to obtain potassium (Knapp).
The atomic structure of potassium is relatively small compared to other elements.
Potassium consists of nineteen protons and nineteen electrons, and twenty neutrons. The
electron configuration of potassium is [Ar] 4S1. The complete writing out version can be seen
in appendix B. The electron dot diagram has one dot, which represent the one valence
electron. For a picture of the dot diagram, see appendix B. Potassium only has one state of
oxidation, plus one. When put with water potassium it makes potassium hydroxide and
hydrogen gas. This is a quick reaction and does not take very long. The equation for this is
2K + 2H2O
2KOH +H2. Another reaction is one with acids. Potassium dissolves quickly in
sulfuric acid. This form K(I) ion with hydrogen gas. This equation is 2K+H2SO4
2K++SO32-+H2. (Emsley)
One of potassium's compounds is sometimes used in certain types of storage batteries
and in the manufacturing of liquid soap (Baker).This compound is called potassium
hydroxide. Another, potassium nitrate, is used for rock salt and looks like table salt.
Potassium nitrate is also used in fertilizers containing potassium (Baker). One of its biggest
uses is in fireworks and gun powder (Baker). Potassium bicarbonate is found in baking soda,
baking powder, antacids, soft drinks and fire extinguishers. Potassium bromide is used in
photographic film and engraving (Baker). Potassium is mined in Stassfurt, Germany and in
the United States (Knapp-Vol. 18).
Potassium was the first metal that was isolated by electrolysis. "When using
electrolysis, an electrical current creaks down the compound into its element" (Baker).
Potassium in its pure form has few uses. However, compounds of potassium have many
important uses; the most important is as a fertilizer. Potassium with sodium is used as a heattransfer in nuclear reactors. The alloy is liquid at high temperatures. It is also a good agent
used in chemistry labs as it is a great reducing agent (Winter). Potassium hydroxide is used
in the preparation for liquid detergents. Potassium is widely used in anti- freezing agents,
fertilizers metal casting and welding and soldering agents. Potassium helps regulate blood
pressure and heart function. It is also helpful in the contraction of nerves and
muscles (Baker). Kidneys control the amount of potassium in your body (Knapp-Vol.2). In
the economy today, you can buy metallic potassium is available for about $1200 per kg or
$75 per g (Lide).
Plant survival is based on the presence of potassium. It affects the soil health, plant
growth and animal nutrition. It affects cell size, therefore causing photosynthesis and energy
production as well as carbon dioxide supply. Low potassium causes restricted growth,
reduced flowering, and lower quality produce. Higher levels can cause damage therefore
inhibiting absorption of other minerals (Baker).
Potassium has twenty four isotopes. The three main ones are potassium-39, potassium-40,
and potassium-41. The isotope potassium-39 is a stable one. In the isotope potassium-40, it is
unstable and is radioactive and has a half life by beta decay of 1.277 x 109 years. The isotope
potassium-41 is also a stable one (“Periodic Table of Elements”).
For separation scheme, begin with a water solution. Putting in sodium nitrate
(NaNO3) into the water solution will start everything off. Then put sodium chlorate
(Na(ClO3)3). The chlorate in that solution will then combine with silver (Ag) to make an
insoluble salt. Then put in sodium hydroxide (NaOH) into the solution. The hydroxide will
make the aluminum (Al) an insoluble solution with as well. Then test the potassium using a
flame test. The can be seen in appendix D. The disposals of these items are safe in any way.
Elements have been known around the world for many years now, one of these
elements being the element potassium. Potassium is found in many different ways and in
different places around the world. The element potassium has different chemical
compositions than other elements on the periodic table. Potassium also has a different number
of protons, neutrons, and electrons than elements around it on the periodic table. Every
element is different in many different ways, these are the differences of potassium.
Works Cited
Baker, Lawrence W., and David E. Newton. "Potassium." P - Z. Detroit, Mich. [u.a.: U.X.L,
1999. 443-51. Print.
Emsley, John. The Elements. 2nd ed. Oxford: Clarendon, 1994. Print.
Knapp, Brian J. Potassium to Zirconium. Vol. 18. Danbury, CT: Grolier Educational, 2002.
Print. Elements.
Knapp, Brian. Sodium and Potassium. Vol. 2. Danbury, CT: Grolier Educational, 2002.
Print. Elements.
Lide, David R. CRC Handbook of Chemistry and Physics. Boca Raton, FL: CRC, 2008.
Print.
"Potassium | Historical Information." WebElements Periodic Table of the Elements. Web. 19
Dec. 2010. <http://www.webelements.com/potassium/history.html>.
"Potassium | Chemical Reaction Data." WebElements Periodic Table of the Elements. Web.
19 Dec. 2010. <http://www.webelements.com/potassium/chemistry.html>.
“Periodic Table of Elements.” EnvironmentalChemistry.com. J.K. Barbalace, inc., 2011.
Web. 19 Dec. 2010. <http://environmentalchemistry.com/yogi/periodic/Kpg2.html#Nuclides>.
Appendix A
Decay
Atomic
Nuclide
Mass
Abun
NN
%
K32
32.022
13
Syn
K33
33.007
14
Syn
K34
33.998
15
Syn
K35
34.988
16
Syn
K36
35.9813
17
Syn
Spin
Half Life
3/2+ 190ms
2+
DM
DT
ε + P Cl34
BR
Energy
%
(MeV)
0.37
5.984
190ms
ε
342ms
ε + P Cl35
0.05
4.299
342ms
ε + α S32
0.0034
6.166
342ms
ε
Ar36
12.805
ε
Ar37
6.149
11.881
Ar35
K37
36.9734
18
Syn
3/2+ 1.226s
K38
37.9691
19
Syn
3+
7.636m
ε
Ar38
5.913
Syn
0+
923.9ms
ε
Ar38
6.043
1.277E 9y
β-
Ca40
89.28
1.311
1.277E 9y
ε
Ar40
10.72
1.505
meta state 0.130MeV
K39
38.9637
20
93.258
3/2+ Stable
K40
39.964
21
0.012
4-
K41
40.9618
22
6.73
3/2+ Stable
β-
Ca42
3.525
β-
Ca43
1.815
β-
Ca44
5.660
3/2+ 17.3m
β-
Ca45
4.204
Syn
2-
105s
β-
Ca46
7.716
28
Syn
1/2+ 17.5s
β-
Ca47
6.643
29
Syn
2-
K42
41.9624
23
Syn
2-
K43
42.9607
24
Syn
3/2+ 22.3h
K44
43.9616
25
Syn
2-
K45
44.9607
26
Syn
K46
45.962
27
K47
46.9617
K48
47.9655
K49
48.9675
30
Syn
12.360h
22.13m
6.8s
β- + N Ca47
6.8s
β-
3/2+ 1.26s
1.14
12.090
Ca48
β- + N Ca48
1.26s
β-
472ms
β- + N Ca49
472ms
β-
365ms
β- + N Ca50
365ms
β-
105ms
β- + N Ca51
105ms
β-
2.144
86
5.820
10.970
Ca49
1-,
K50
49.973
31
Syn
29
7.900
214.200
Ca50
2+,
K51
50.976
32
Syn
47
9.500
3/2+
K52
K53
51.983
52.987
33
34
Syn
Syn
3/2+ 30ms
13.900
Ca51
>88
Ca52
β- + N Ca52
85
K54
K55
53.994
54.99
35
36
Syn
30ms
β-
10ms
β- + N Ca53
10ms
β-
Ca53
Ca54
>0
14.200
18.000
Syn
(“Periodic Table of Elements”)
Appendix B
𝐾∙
(Lewis dot diagram is self generated)
Appendix C
1s2 2s2 2p6 3s1 3p6 4s1
Appendix D
Put in NaNO3
(Sodium
Nitrate)
Start with water
solution (H2O)
Then put in Na(ClO3)3
(Sodium Chlorate)
Then test the
potassium with a
flame test.
This will react with the
chlorate making silver
chlorate, which is insoluble.
This will react with the
hydroxide making
aluminum hydroxide, which
is insoluble.