Bismuth (Bi): Element Information, Properties And Uses

Overview

Bismuth is a chemical element with the symbol Bi and atomic number 83. Bismuth is hard, brittle, lustrous and coarsely crystalline. It can be distinguished from all other metals by its color- gray-white with a reddish tinge. Bismuth is usually mixed with other metals such as lead, tin, iron or cadmium to form low-melting alloys. These alloys are used in things such as automatic fire sprinkler systems, fire detection systems and electrical fuses.

Bismuth also has high electrical resistance for a metal. It has the lowest values of thermal conductivity than any metal, except mercury. It is also stable to oxygen and water but dissolves in concentrated nitric air. All bismuth salts form insoluble compounds when put into water.

What You Need To Know About Bismuth

Discovery

Bismuth was discovered by unknown alchemist around 1400 AD. Later in the same centaury it was alloyed with lead to make cast type for printers and decorated caskets were being crafted in the metal. Bismuth was often confused with lead; it was likewise a heavy metal with a relatively low melting temperature point. French chemist Claude Geoffroy  the Younger was the first to prove that bismuth was distinct from lead in 1753.

 Natural Occurrence

Naturally occurring bismuth is found in small quantities throughout Earth’s crust both as a pure metal and combined with other elements in various compounds. The main source of bismuth is found in the mineral bismuthinite or bismuth sulfides (Bi₂S₃). Bismuth is typically obtained as a by-product in reefing lead, copper, tin, silver and gold ores found in Bolivia, Peru, Japan, Mexico and Canada, England and Germany.  Bismuth is produced in the United States only as a by-product of lead refining in Nebraska.

Periodic Table Facts

• The atomic symbol  of Bismuth on the periodic table of elements is Bi
• In the periodic table, Bismuth is located in group 15 (pnictogens), period 6, p-block.
• Bismuth is categorized as a Post-transition metal in the periodic table.
• The atomic number of Bismuth is 83. Atomic number is the number of protons.
• The ground state electronic configuration of neutral Bismuth is [Xe]4f¹⁴ 5d¹⁰ 6s² 6p³
• Electrons per shell in Bismuth are 2, 8, 18, 32, 18, 5.

Physical Properties

• Bismuth is solid at room temperature.
• Bismuth is stable to both dry and moist air at ordinary temperatures.
• Bismuth is a brittle, crystalline, white metal with a slight pink tinge.
• The melting point of Bismuth is 271^oC (520.53^oF).
• Boiling point of Bismuth is 1564^oC (1837K, 2847^oF).
• Density of Bismuth is 9.79 grams per cubic centimeter (5.6 ounces per cubic inch). It is denser in the liquid phase than in the solid phase.
• The heat of fusion of Bismuth is 11.30 kJ/mol
• The heat of vaporization of Bismuth is 179 kJ/mol
• Bismuth has a Molar heat capacity of 25.52 kJ/mol
• When burned in oxygen, bismuth burns with a blue flame and its oxide forms yellow fumes.

Other Properties

• Element bismuth occurs naturally as the metal itself and is found as crystals in the sulphide ores of nickel, cobalt, silver and tin.
• Bismuth is the most naturally diamagnetic element and has one of the lowest values of thermal conductivity than any other metal except mercury.
• Bismuth has a high electrical resistance and has the highest Hall-effect of any metal (that is, the greatest increase in electrical resistance when placed in a magnetic field.
• All bismuth salts form insoluble compounds when put into water.
• The atomic number of Bismuth is 83. Atomic number is the number of protons in the nucleus.
• The atomic weight of Bismuth is 208.98040. Atomic weight is the average mass of the atom.
• Bismuth forms trivalent and pentavalent compounds, the trivalent ones being more common.
• The electronegativity of Bismuth according to the Pauling scale is 2.02
• The first, second and third Ionization energies of Bismuth is 703 kJ/mol, 1610 kJ/mol and 2466 kJ/mol respectively.
• Bismuth has an Atomic radius of 156 pm and Van der Waals radius of 207 pm.
• Bismuth has a rhombohedral crystal structure.
• Bismuth has 33 isotopes with mass numbers ranging from 185 to 217. Of these only 209-Bismuth is considered to be effectively stable, although it is actually radioactive with an extremely slow rate of alpha particle decay: its half-life is 1.9 X 10¹⁹ years.

Extraction

Pure bismuth can be obtained by reducing the oxide with carbon or by roasting the sulfide in the presence of charcoal and metallic iron to remove the sulfur.

Bismuth metal is often separated from ores of other metals by the Betterton-Kroll process. Calcium or magnesium is added to the molten (Melted) ore where it forms an alloy with bismuth. Later, the bismuth can be separated from the calcium or magnesium to make the pure metal.

Reactions

Bismuth is stable to both dry and moist air at ordinary temperatures. However, when red-hot, it reacts with water to produce bismuth III oxide.

2Bi + 3H₂O―> Bi₂O₃ + 3H₂ 

Bismuth also reacts with fluorine to make bismuth (V) fluoride at 500oC or bismuth (III) fluoride at lower temperatures.

Bi + F―> BiF₃

Bismuth dissolves in hydrochloric acid in the presence of oxygen to produce Bismuth (III) chloride and water.

4Bi +3O₂ +12HCl ―> 4BiCl₃ + 6 H₂O

Bismuth dissolves in concentrated sulfuric acid to produce bismuth (III) sulphate and sulfur dioxide.

6H₂SO₄ +2Bi―> 6H₂O +Bi₂(SO₄)₃ + 3SO₂

Bismuth reacts with nitric acid to produce bismuth (III) nitrate.

Bi + 6HNO₃ ―> Bi (NO₃)₃ +3NO₂ +3 H₂O

Uses of Bismuth

• Bismuth is used as a transmetalating agent in the synthesis of alkaline-earth metal complexes.
• Bismuth is used as an ingredient in some pharmaceuticals like stomach upset medicines.
• Bismuth metal is used in the manufacture of low melting solders and fusible alloys as well as low toxicity bird shot and fishing sinkers.
• Compounds of bismuth such as Bismuth oxychloride (BiOCl) is sometimes used in cosmetics as a pigment in paint for eye shadows, hair sprays and nail polishes.
• Bismuth is used in metal alloys with other metals such as iron. These alloys are used in automatic sprinkler systems for fires.
• Bismuth can also be used as a replacement for lead (Pb) in many ballistics and weighting applications. This is because the density difference between lead and bismuth is very small.
• Bismuth is used to make free-machining steels and free-machining aluminum alloys for precision machining properties.
• Bismuth is also used in aluminum-silicon cast alloys in order to refine silicon morphology.
• Compounds of bismuth such as Bismuth germinate is used as a scintillator, widely used in X-ray and gamma ray detectors.
• Bismuth is also used as an ingredient in lubricating greases.
• Bismuth compounds are used as a catalyst in the manufacturing of acrylonitrile, the starting material for synthetic fibers and rubbers.
• Bismuth oxide (BiO₃), a bismuth compound is used as a yellow pigment in paints and cosmetics.
• Bismuth has also replaced the toxic lead in many applications such as plumbing, bullets, birdshot, metal alloys, soldering and other applications.

Health & Environmental Effects

• Bismuth metal is not considered toxic and poses minimum threat to the environment. Bismuth compounds generally have very low solubility but they should be handled with care as there is only limited information on their effects and fate in the environment.

Summary Of Properties Of Bismuth In Tabular Form