Antimony is a chemical element (Sb, atomic number 51) recognized as a metalloid. Its history is extensive, stretching back thousands of years before its formal scientific identification. Unlike many elements, antimony’s “discovery” doesn’t point to a single individual or moment; its understanding evolved gradually over centuries through various contributions.
Antimony Through the Ages
Ancient civilizations used antimony compounds, primarily stibnite. In ancient Egypt, 5,000 years ago, stibnite was ground into kohl, a popular black eye makeup. It also had medicinal uses. A 5,000-year-old antimony vase in the Louvre provides evidence of its early use.
In Babylonian and Chaldean civilizations, from 4000 BCE, antimony compounds were used in decorative elements like glazes for ornamental bricks. The Chaldeans used yellow lead antimonite in the 6th and 7th centuries BCE. Across Asia, particularly in China, antimony compounds were used in traditional medicine and for creating alloys.
Greek and Roman scholars, such as Pliny the Elder and Dioscorides (1st century CE), documented antimony compounds’ medicinal properties, including treating skin conditions. Pliny distinguished “male” and “female” forms, likely referring to the sulfide and metallic forms. During medieval times, antimony’s use expanded to hardening lead for printing type and in medicinal laxative pills.
The Scientific Identification of Antimony
The isolation and recognition of antimony as a distinct chemical element progressed over centuries. Vannoccio Biringuccio documented the earliest Western procedure to isolate antimony in his 1540 book, De la pirotechnia. This marked a significant step in distinguishing it from other substances.
A notable, though controversial, figure associated with antimony is Basil Valentine. The book Currus Triumphalis Antimonii (The Triumphal Chariot of Antimony), published in Germany in 1604, described the preparation of metallic antimony and was attributed to him. However, the authenticity of his identity as a 15th-century Benedictine monk and the authorship of his works are widely debated.
Andreas Libavius, a German chemist, made a definitive contribution in 1615. He described obtaining metallic antimony by adding iron to a molten mixture of antimony sulfide, salt, and potassium tartrate. His work fostered a more analytical approach.
French chemist Nicolas Lémery extensively studied antimony, publishing his Treatise on Antimony in 1707. Lémery’s systematic descriptions of its preparation and properties aided its proper classification. The 17th and 18th centuries were important for recognizing antimony as a fundamental substance, culminating in Anton von Swab’s description of naturally occurring pure antimony in 1783.
Antimony: Properties and Modern Uses
Antimony is classified as a metalloid. In its most stable form, it appears as a lustrous, silvery-gray solid, brittle with a flaky texture. It maintains stability in dry air at room temperature and resists dilute acids or alkalis. While expanding upon solidification, antimony is a poor conductor of both heat and electricity. It commonly exhibits oxidation states of +3 and +5, influencing its chemical reactivity.
Antimony compounds are used today, with flame retardants a prominent application. Antimony trioxide (Sb₂O₃) and antimony pentoxide (Sb₂O₅) are often combined with halogenated compounds, enhancing fire resistance in plastics, textiles, and rubber. This makes materials safer by reducing their flammability.
Antimony is a component in various alloys, enhancing other metals’ properties. When alloyed with lead (0.5% to 12%), it increases hardness, strength, and durability, suitable for car batteries, solders, bullets, and cable sheathing. Antimony is also used in the electronics industry as a dopant in semiconductors, including infrared detectors and diodes.
While historically used in medicine, antimony and many of its compounds are known to be toxic, with effects similar to arsenic poisoning. Exposure can lead to respiratory irritation, gastrointestinal issues, and heart problems. Antimony trioxide is classified as possibly carcinogenic to humans, underscoring the need for careful handling and controlled exposure.