- Antimony (Sb) is a metalloid with atomic number 51, located in Group 15 of the periodic table alongside nitrogen, phosphorus, arsenic, and bismuth.
- It exhibits properties intermediate between metals and nonmetals, appearing as a lustrous, silvery-gray crystalline solid that is brittle and easily pulverized.
- Antimony has five valence electrons—two in the 5s subshell and three in the 5p subshell—and most commonly exhibits oxidation states of +3 and +5, with +3 being the more stable. Its atomic structure consists of fifty-one protons, typically seventy-one neutrons, and fifty-one electrons arranged in five shells.
- Naturally occurring antimony consists of two stable isotopes: antimony-121 (¹²¹Sb), which makes up 57.36% of natural antimony, and antimony-123 (¹²³Sb), which accounts for the remaining 42.64%.
- Antimony is relatively rare in the Earth’s crust, with an average abundance of about 0.2 parts per million. It is primarily obtained from the sulfide mineral stibnite (Sb₂S₃), though it also occurs in other minerals such as valentinite (Sb₂O₃). Major producing countries include China (by far the largest producer), Russia, Tajikistan, and Bolivia.
- Antimony has been known since ancient times, with early references dating back to around 3000 BCE. It was used in cosmetics such as kohl, an eye cosmetic popular in ancient Egypt and the Middle East. The name “antimony” is derived from the Greek anti-monos, meaning “not alone,” referring to its frequent occurrence in combination with other elements. Its chemical symbol Sb comes from the Latin stibium, the ancient name for stibnite.
- In modern industry, antimony is mainly used as an alloying element to harden lead and increase its strength and durability, particularly in lead–acid batteries. It is also used in flame retardants, often in the form of antimony trioxide (Sb₂O₃), which works synergistically with halogenated compounds to inhibit combustion. Other uses include semiconductors, infrared detectors, low-friction metals, and solders.
- Chemically, antimony forms covalent compounds with both metals and nonmetals. Antimony trioxide (Sb₂O₃) is its most commercially important compound, used as a flame retardant and opacifying agent in glass and ceramics. Antimony pentachloride (SbCl₅) and antimony trifluoride (SbF₃) are important in organic synthesis and as catalysts. In its elemental form, antimony is relatively inert at room temperature but oxidizes upon heating.
- Biologically, antimony has no known essential role in humans. Some of its compounds, particularly antimony trioxide and certain antimonial drugs, can be toxic if inhaled or ingested in significant amounts. Historically, antimony compounds have been used medicinally, particularly in the treatment of parasitic diseases such as leishmaniasis, though modern medicine uses them with great caution due to their toxicity.
- From an environmental perspective, antimony mining and smelting can lead to soil and water contamination, particularly near stibnite ore deposits. Some antimony compounds are persistent in the environment and may pose risks to aquatic life. Recycling from lead–acid batteries and other antimony-containing products is an important source of secondary supply and helps mitigate environmental impacts from primary mining.
