Antimony (Sb): Atomic number: 51, Atomic mass: 121.75 g.mol -1, Electronegativity: 1.9, Density: 6.684 g.cm-3, Melting point: 631 °C, Boiling point: 1380 °C, Vanderwaals radius: 0.159 nm, Ionic radius: 0.245 nm (-3); 0.062 nm (+5); 0.076 nm (+3), Isotopes: 12, Electronic Shell: [ Kr ] 4d10 5s25p3, Energy of first ionisation: 834 kJ.mol -1, Energy of second ionisation: 1595 kJ.mol -1, Energy of third ionisation: 2443 kJ.mol -1, Standard potential: 0.21 V ( Sb3+/ Sb), Discovered by: The ancients. Antimony si a semimetallic chemical element which can exist in two forms: the metallic form is bright, silvery, hard and brittle; the non metallic form is a grey powder. Antimony is a poor conductor of heat and electricity, it is stable in dry air and is not attacked by dilute acids or alkalis. Antimony and some of its alloys expand on cooling. Antimony has been known since ancient times. It is sometimes found free in nature, but is usually obtained from the ores stibnite (Sb2S3) and valentinite (Sb2O3). Nicolas Lémery, a French chemist, was the first person to scientifically study antimony and its compounds. He published his findings in 1707. Antimony makes up about 0.00002% of the earth's crust. Applications: Very pure antimony is used to make certain types of semiconductor devices, such as diodes and infrared detectors. Antimony is alloyed with lead to increase lead's durability. Antimony alloys are also used in batteries, low friction metals, type metal and cable sheathing, among other products. Antimony compounds are used to make flame-proofing materials, paints, ceramic enamels, glass and pottery. The ancient Egyptians used antimony, in the form of stibnite, for black eye make-up. Antimony in the environment: Antimony occurs naturally in the environment. But it also enters the environment through several applications by humans. Antimony is an important metal in the world economy. Annual production is about 50.000 tonnes per year, with virgin materials coming mainly from china, Russia, Bolivia and South Africa. World reserves exceed 5 million tonnes. In Finland there is a deposit of elemental antimony.