The Element Bismuth
The element bismuth was officially discovered in 1753 by Claude Geoffrey Junine, but has been utilized since the Middle Ages and in Ancient Egypt. It is a hard and brittle metallic element found in Group 15 of the periodic table. One of its distinguishable features is its slightly reddish-pinkish tinge on its white, crystalline metal.
Everyday products, such as eyeshadow, Pepto-Bismol, and fire sprinklers all contain the element. Let’s learn more about this!
Some Cool Facts About Bismuth
- Similarly to other post-transition metals, bismuth’s electric and thermal conductivity is very low for a metal.
- The metal is stable to oxygen and water. It does not tarnish when exposed to air and forms an insoluble compound when put in water.
- At boiling point, the element oxidizes rapidly and forms an oxide coating. This coating is a distinguishable yellow.
- While this element is relatively inactive, it reacts sensitively with dilute and concentrated nitric acid. When combined, bismuth (III) nitrate, nitric oxide, and water form.
- In the environment, bismuth occurs in the Earth’s crust and is twice as abundant as gold.
- The metal is mostly obtained as a by-product during the production of other metal ores, like lead and copper. Some countries, such as Japan, Bolivia, and Mexico mine it as well. However, this method only acquires small quantities. Bismuth can also be extracted from Pepto-Bismol tablets.
- Bismuth’s name comes from the German word “wissmuth” and the Latin word “bisemutum”, which means white mass.
- The Incas utilized bismuth by combining it with copper and tin to produce knives. Ancient Egypt used bismoclite for cosmetic purposes.
- Bismuth-209 is an isotope. Scientists used to think it was the heaviest stable isotope. However, studies have actually found that bismuth-209 is unstable and decays into thallium-205 through alpha decay. It has a half-life of about 20,000,000,000,000,000,000 years and is very weakly radioactive.
- Bismuth is one of few elements that is denser as a liquid than as a solid. It has a liquid density of 10.05 g/cm³
- Bismuth is next to lead in the periodic table, and shares some properties with lead, for example a high density, and a low melting point. One important difference is bismuth is far less toxic, which is why it is used as a non-toxic shot for shotguns.
Important Properties of Bismuth
Bismuth is a post-transition metal that is part of the nitrogen (learn more about nitrogen’s discovery here) group on the periodic table. Post-transition metals are soft and poor conductors in general, and bismuth follows periodic trends, but bismuth has even lower conductivity properties compared to the rest. It forms low melting alloys with other metals, like tin and iron, due to its low melting point of 271.40°C (520.52°F). These alloys are utilized to create common products, such as fire extinguishers, shotguns, and even fishing sinkers.
In its solid state, bismuth retains the ferromagnetic properties, or structural memories, of its liquid state. When it is melted to liquid-state and cooled back to solid-state, the solid-state remembers the structure of the liquid state. Furthermore, solid bismuth is the most diamagnetic metal. This means that the magnetic field repels the metal. However, when under certain high pressure and temperature conditions, it turns to liquid and becomes ferromagnetic. This means that the magnetic field attracts the element.
Pure bismuth melts easily and can form beautiful crystals. How? When the liquid form freezes, it expands, forming crystals. This is a unique feature, as most materials contract as they solidify. These crystals are silver and quickly oxidize to produce unique rainbow colors. Learn how you can make these crystals at home here!
Bismuth has 41 isotopes. One of these isotopes, Bismuth-213, is used as a therapeutic radionuclide in targeted alpha-therapy to treat various cancers.
Bismuth-213 has a short half-life of 46 minutes. When bismuth-213 emits an alpha particle, it decays into thallium-209. When it emits a beta particle, it becomes polonium-213.
Bismuth Element in Nature
Small quantities of bismuth exist in the Earth’s crust. Out of all the elements in the nitrogen group, it is the least abundant making it relatively rare. The two most important ores are bismuthimite and bismite, which both contain the element. Bismuth mining and refining mainly takes place in China and Vietnam.
Bismuth’s Applications in Today’s World
Bismuth is a versatile element that has applications in the following fields: pharmaceutics, cosmetics, lead substitution, alloys, and synthetic fibers.
When you have a stomach ache or diarrhea, what do you usually reach for? Many turn to Pepto-Bismol, the brand name of bismuth subsalicylate (C7H5BiO4). Interestingly, bismuth has no known natural biological role, yet it has been used in medicine since the 18th century. Today, the most well-known application is Pepto-Bismol, which is an antidiarrheal agent used to treat gastrointestinal symptoms. Bismuth subsalicylate is a type of chelated salt-complex, which are known to boost absorption; Being the active ingredient in Pepto-Bismol, it works by stimulating the absorption of fluids and electrolytes across the intestinal wall.
Cosmetics and Pigment
You may have heard of mineral makeup and of all its claims of being a “cleaner” and “purer” choice for your skin. Bismuth oxychloride is commonly added to mineral makeup; It is made by combining bismuth with chloride and water. This compound is not only inexpensive but gives off a beautiful, shimmery, pearlescent appearance to give a glowy finish. Additionally, it feels nice and soft and the skin. However, consumers should steer away from bismuth-containing cosmetics. This chemical is a heavy metal that can cause irritation and inflammation.
Bismuth nitrates are commonly used as a pigment and are the starting material for bismuth vanadate pigments. Bismuth vanadate is a brightly, yellow-colored solid that is nontoxic, stable, and resistant to different weathers. These benefits make it ideal for architectural and industrial uses, coil, and powder coatings. It is also an amazing hiding powder, which as the name implies, hides the surface of an object.
Bismuth is a “green” element. In the environment, this metal is non-toxic and does not pose an industrial hazard. The manufacturing industry often substitutes harmful lead with safe bismuth metal, as they share common characteristics, such as similar densities. It commonly replaces the lead found in shotgun ammunition in order to prevent any risk of lead contamination in the waters that are used for bird hunting.
Adding bismuth to an alloy will decrease the melting temperature. Low melting alloys are commonly used in electronics that need to be heat-resistant, such as fire sprinklers, fire alarms, and boiler plugs. Additionally, bismuth expands in volume by 3.3% when changing from a liquid to a solid state. When added to an alloy, it will prevent solidification shrinkage. This helps to prevent the inability for it to be reused.
Lastly, bismuth compounds are the catalyst in producing acrylonitrile, which is the starting material for synthetic fibers and rubbers.
History of Bismuth
Bismuth is an ancient element. It was one of the first ten metals to be discovered. In the beginning, scientists believed bismuth to be an alloy of tin and lead. Then, a French chemist named Claude Geoffroy finally distinguished bismuth as its own element in 1753.
Bismuth + Acids
When added to strong acids like sulfuric acid (H2SO4), nitric acid (HNO3), or hydrochloric acid (HCl), bismuth dissolves and forms the bismuth(III) ion. These three acids differ from each other in how quickly they will dissolve bismuth. HNO3 most rapidly dissolves the metal, while HCl has the slowest effect.
Bismuth + Bases
Ammonia and sodium hydroxide react with bismuth(III) to form Bi(OH)3. When these bases react with bismuth(III), it results in a precipitation reaction and forms an insoluble salt.
Bismuth + Water
Bismuth reacts with vaporized water and forms trioxide bismuth(III) oxide (Bi2O3). It is important to note that in order for this reaction to take place, bismuth must be “red hot”, meaning that solid bismuth is so hot that it turns red. Cold, air-free water does not react with bismuth.
Bismuth + Halogens
The halogen family includes fluorine, chlorine, bromine, and iodine. When bismuth reacts with a halogen, it forms a trihalide. For example: 2 Bi(s) + 3 F2(g) → 2 BiF3.
Bismuth + Metals
Stannite is a mineral that reduces bismuth(III) under alkaline conditions. Bismuth will turn into small black particles. An important step that is important to the success of this reaction is the preparation of the stannite ion. The preparation process must take place just before usage and consists of treating a solution of tin(II) chloride with excess sodium hydroxide.
While pure bismuth can be found in nature, it is more common for it to be found in compounds. The bismuth atom is tricovalent and pentacovalent, and therefore forms trivalent and pentavalent compounds. What does this mean? If the atom is forming a trivalent compound, for example, it means that three electrons are being shared between two atoms. This can be explained by the electron shell configuration of bismuth, which is: [Xe] 4f145d106s26p3. This shows that the atom has five valence electrons. Furthermore, bismuth uses three 6p electrons in bond formation.
There are a few different types of naturally occurring bismuth compounds: oxides, sulfides, and carbonates. Bismite, Bi2O3 is a greenish-yellow oxide that is the product of burning bismuth metal reacting with oxygen. Bismuthinite, Bi2S3 is a greyish-white sulfide found in bismuth ores. These two compounds are considered to be the most important and common ores of bismuth; Bismite contains 89.7% bismuth and bismuthinite contains 81.3%. Bismuth carbonates include bismutite, (BiO)2CO3, and bismutosphaerite. They are insoluble in water and are useful because they are able to be converted to other bismuth compounds, like oxides, upon heating.
Bismuthine, BiH3 is a hydride. It is an endothermic compound that has a low boiling point of 17˚C (62.6˚F). In its gas phase, this compound is unstable under normal pressure; It is stable only at temperatures below -60˚C (-76˚F) and spontaneously decomposes at room temperature. Unlike the other bismuth hydrides, such as BiH4 or BiH5, BiH3 does not become more thermodynamically stable with increasing pressure.
Bismuth is normally found in an oxidation state of +3. In this state, the atom reacts with halogens to form trihalides. These halogens include fluorine, chlorine, bromine, and iodine, which form BiF3, BiCl3, BiBr3, and BiI3. With the exception of BiF3, these compounds hydrolyze in water.
Bismuth (III) iodide reacts with excess iodide ions to form a nicely-orange colored tetraiodobismuthate ion, BiI4–
Synthesis of Bismuth
A widely used method of extracting the element bismuth is the Betterton-Kroll process. First, calcium and magnesium are added to a molten lead-bismuth bath. This forms a bismuth compound, which has a higher melting point and lower density compared to lead. These two properties allow for the lead to be separated and removed. Then, chlorine is added to isolate pure bismuth metal from calcium and magnesium.
To extract bismuth from its ores, like bismite and bismuthinite, there is a dry process that takes place. Oxides and sulfides are easily reduced, while bismuth has a low melting point, making extraction easy. There is a dry process that takes place to accomplish the separation of pure bismuth metal. First, the ores are heated to melt bismuth. This melting step is repeated a second time, but with the addition of reducing agents, such as carbon for bismite and ethanol for bismuthinite. The reducing agents will work to get rid of the oxide or sulfide.
In the home lab, bismuth metal can be produced from a solution of bismuth (II) chloride by simply adding aluminum foil. It is best to keep the solution acidic to prevent the bismuth (III) chloride from hydrolyzing.
Bismuth Oxidation States
Bismuth is mostly found in a +3 oxidation state, but is also seen in a +5 state, and very rarely -3 and +2. BiF5 and NaBiO3 are two well-known bismuth +5 compounds, but they are made only with difficulty.
Properties of the Element Bismuth
- Symbol: Bi
- Melting point: 271.4°C
- Boiling point: 1,564°C
- Density (g cm−3): 9.747
- Atomic mass: 208.98 amu
- Atomic number: 83
- Electronegativity (Pauling Scale): 2.02
- Classification: Post-transition metal in group 15 of the periodic table
- Electron configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³
- Key Isotopes: Forty-five known isotopes, none of which are stable, but one of which is long lasting 2.01×1019 years, more than a billion times the age of the universe (209Bi)
- Toxicity: Bismuth is not known to be toxic, and as much as 15g can be tolerated by an adult, but long-term exposure may lead to adverse health effects
Where can I Bismuth?
Chunks of bismuth metal can be found on Amazon, eBay, and specialty websites.