Antimony
Definition and meaning of Antimony in chemistry.
![Antimony element card: symbol Sb, atomic number 51, atomic mass 121.76, electron configuration [Kr] 4d¹⁰ 5s² 5p³, oxidation states +5 +3 -3, Metalloid, group 15, period 5, solid at room temperature.](/assets/images/terms/antimony-chemical-element.webp)
Antimony is a shiny, silvery-gray metalloid with the chemical symbol Sb and atomic number 51. This hard, extremely brittle solid shows physical and chemical properties of both true metals and nonmetals. Its symbol comes from 'stibium,' the ancient Latin name for antimony sulfide.
In more detail
Antimony belongs to group 15 on the periodic table. Scientists call this specific group the pnictogens. As a metalloid, antimony conducts heat and electricity poorly compared to standard metals.
In nature, it mostly exists as the dark mineral stibnite (Sb2S3). People do occasionally find it in its pure elemental form within certain rock deposits. In chemical reactions, antimony typically shows oxidation states of +3 and +5.
An oxidation state tells us how many electrons an atom shares or moves. It easily forms complex oxides, halides, and organometallic compounds. When heated in normal air, the metalloid burns very brightly.
This vigorous reaction produces thick, dense white fumes of antimony trioxide (Sb2O3). Antimony also has a highly unusual physical trait. Like liquid water, it expands slightly when it freezes from a liquid into a solid.
Most other materials shrink when they freeze. This rare expanding property makes it very useful in industrial manufacturing. It helps workers cast sharp, highly detailed metal alloys like type metal.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Sb |
| Atomic number | 51 |
| Atomic mass | 121.76 u |
| Category | Metalloid |
| Melting point | 630.63 °C |
| Common mineral | Stibnite |
Manufacturers often mix antimony with lead to create a special alloy. An alloy is a solid blend of two or more elements. This specific mixture greatly increases the lead's hardness and mechanical strength. Companies use this tough material to build sturdy grids inside modern lead-acid car batteries. They rely on it to make long-lasting power sources.
Frequently asked questions
Is antimony considered a true metal?
No, antimony is formally classified as a metalloid. This means it possesses a unique mixture of both metallic and nonmetallic traits.
Why is antimony frequently added to metal alloys?
It increases the overall hardness and strength of soft metals like lead. It also prevents shrinkage during casting because it expands when it freezes.
Related terms
Sources & references
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