ANTIMONY: HISTORY, STRUCTURE, PROPERTIES, USES AND RISKS - CHEMISTRY - 2025

The Antimony is a metalloid shiny, silver, and with some bluish hue. Its solid is also characterized by being very brittle and flaky in texture. It belongs to group 15 of the periodic table, headed by nitrogen. After bismuth (and moscovium), it is the heaviest element of the group.

It is represented by the chemical symbol Sb. In nature it is found mainly in stibite and ullmannite mineral ores, the chemical formulas of which are Sb ₂ S ₃ and NiSbS, respectively. Its high tendency to form sulphides instead of oxides is due to the fact that it is chemically soft.

Crystalline antimony. Source: Best Sci-Fatcs

On the other hand, antimony is also physically soft, presenting a hardness of 3 on the Mohs scale. It is stable at room temperature and does not react with oxygen in the air. But when heated in the presence of oxygen, it forms antimony trioxide, Sb ₂ O ₃.

Likewise, it is resistant to the action of weak acids; but when hot it is attacked by nitric and hydrochloric acids.

Antimony has numerous applications, among them it is used in alloys with lead and tin, in the manufacture of vehicle batteries, low friction materials, etc.

This metalloid has the rare property of increasing in volume when it solidifies, allowing its alloys to fully occupy the space used to mold the instrument to be manufactured.

History of its discovery

BC

There is evidence that since 3100 BC, antimony sulfide was used as a cosmetic in Egypt. In Mesopotamia, present-day Iraq, remains of a vase and another artifact that, presumably, date between 3000 and 2200 BC, were found in which antimony was used in its manufacture.

Introduction of the term

The Roman scholar Pliny the Elder (23-79 AD) described the use of antimony, which he called stibius, in the elaboration of seven medicines in his Treatise on Natural History. The alchemist Abu Mussa Jahir Ibn Hayyan (721-815) is credited with introducing the term antimony to name the element.

He used the following etymology: 'anti' as a synonym for negation, and 'mono' for only. Then he wanted to emphasize that antimony was not only found in nature. It is already known that it is part of sulfide minerals, as well as many other elements.

Obtaining

The Greek naturist Pedanius Diascorides is believed to have obtained pure antimony, by heating antimony sulfide in a stream of air. The Italian metallurgist Vannocio Biringucio, in the book De la Pirotecnia (1540), makes a description of a method to isolate antimony.

The German chemist Andreas Libavius ​​(1615), by using a molten mixture of iron, antimony sulfide, salt, and potassium tartrate, achieved the production of a crystalline antimony.

The first detailed report on antimony was made in 1707 by the French chemist Nicolas Lemery (1645-1715), in his book Treatise on Antimony.

Structure of antimony

Wrinkled layers that make up the crystal structure of metallic or silver antimony. Source: Materialscientist

The upper image shows the wrinkled layered structure adopted by arsenic atoms. However, greyish antimony, better known as metallic antimony, also adopts this structure. It is said to be "wrinkled" because there are Sb atoms moving up and down the plane composed of the shell.

These layers, although they are responsible for the photons that interact with it shine silvery brilliance, making antimony pass as a metal, the truth is that the forces that unite them are weak; hence the apparent metallic fragments of Sb can be easily ground and brittle or flaky.

Also, the Sb atoms in the wrinkled layers are not close enough to group their atomic orbitals together and thus create a band that allows electrical conduction.

Looking at a grayish sphere individually, it can be seen that it has three Sb-Sb bonds. From a higher plane, Sb could be seen in the center of a triangle, with three Sb located at its vertices. However, the triangle is not flat and has two levels or floors.

The lateral reproduction of such triangles and their bonds establishes wrinkled layers, which line up to form rhombohedral crystals.

Allotropy

The structure just described corresponds to greyish antimony, the most stable of its four allotropes. The other three allotropes (black, yellow, and explosive) are metastable; that is, they can exist under very harsh conditions.

There is not much information concerning their structures. It is known, however, that black antimony is amorphous, so its structure is messy and intricate.

Yellow antimony is stable below -90ºC, behaves like a non-metallic element, and it can be conjectured that it consists of small agglomerates type Sb ₄ (similar to those of phosphorus); when heated it transforms into the black allotrope.

And with respect to explosive antimony, it consists of a gelatinous deposit formed on the cathode during the electrolysis of an aqueous solution of an antimony halide.

At the slightest strong friction or impact, the soft solid releases so much heat that it explodes and stabilizes as its atoms regroup in the rhombohedral crystalline structure of grayish antimony.

Properties

Atomic weight

121.76 g / mol.

Atomic number

51.

Electronic configuration

4d ¹⁰ 5s ² 5p ³.

Oxidation states

-3, -2, -1, +1, +2, +3, +4, +5.

Physical description

Lustrous silvery solid, brittle, with a scaly surface, with a bluish hue. It can also appear as a black powder.

Melting point

630.63 ° C.

Boiling point

1,635 ° C.

Density

-6.697 g / cm ³ at room temperature.

-6.53 g / cm ³ in liquid state, temperature equal to or greater than the melting point.

Heat of fusion

19.79 kJ / mol.

Heat of vaporization

193.43 kJ / mol.

Molar caloric capacity

25.23 J / mol.K

Electronegativity

2.05 (Pauling scale).

Atomic radio

140 pm.

Hardness

It is a soft element, with a hardness of 3 on the Mohs scale and can be scratched by glass.

Stability

It is stable at room temperature, not experiencing oxidation. It is also resistant to attack by acids.

Isotopes

It has two stable isotopes: ¹²¹ Sb and ¹²³ Sb. In addition, there are 35 radioactive isotopes. The radioactive isotope ¹²⁵ Sb has the longest half-life: 2.75 years. In general, radioactive isotopes emit β ⁺ and β ^- radiation.

Electrical and thermal conductivity

Antimony is a poor conductor of heat and electricity.

Chemical reactivity

It cannot displace hydrogen from dilute acids. Forms ionic complexes with organic and inorganic acids. Metallic antimony does not react with air, but is rapidly converted to oxide in humid air.

Halogens and sulfides readily oxidize antimony, if the process occurs at elevated temperatures.

Applications

Alloys

Antimony is used in alloy with lead to make plates for automobile batteries, improving the resistance of the plates, as well as the characteristics of the charges.

The lead-tin alloy has been used to improve the characteristics of welds, as well as that of tracer bullets and cartridge detonators. It is also used in alloys for coating electrical cables.

Antimony is used in antifriction alloys, in the manufacture of pewter and hardening alloys with low tin content in the manufacture of organs and other musical instruments.

It has the characteristic, shared with water, of increasing in volume when it condenses; Therefore, the antimony present in the alloys with lead and tin, fills all the spaces in the molds, improving the definition of the structures made with said alloys.

Fire retardant

Antimony trioxide is used to make fire retardant compounds, always in combination with halogenated fire retardants, bromides and chlorides.

Fire retardants can react with oxygen atoms and OH radicals, which inhibits fire. These flame retardants are used in children's clothing, toys, aircraft and in car seats.

They are also added in polyester resins, and in fiberglass composites for items used as covers for light aircraft engines.

Antimony compounds that are used as fire retardants include: antimony oxychloride, SbOCl; antimony pentoxide, SbO ₅; antimony trichloride, SbCl ₃; and antimony trioxide, SbO ₃.

Electronics field

It is used in the manufacture of semiconductors, diodes, mid-infrared detectors, and in the manufacture of transitors. High purity antimony, used in semiconductor technology, is obtained by reducing antimony compounds with hydrogen.

Medicine and veterinary

Antimony compounds have been used in medicine since ancient times as emetics and antiprotozoa. Potassium potassium tartrate (tartar emetic) was used as an antischistosome for a long time; being used, in addition, as an expectorant, diaphoretic and emetic.

Antimony salts have also been used in the conditioning of the skin of ruminant animals; such as aniomalin, and lithium antimony thiomalate.

Meglumine antimoniate is a drug used in the treatment of leishmaniasis in external foci of domestic animals. Although, the therapeutic benefits were limited.

Pigments and paints

Antimony compounds are used in the manufacture of paints and opacifier in enamels. They are also used in vermilion, yellow and orange pigments, which are products of the slow oxidation of antimony sulfides.

Some of its organic salts (tartrates) are used in the textile industry to help bind certain dyes.

Antimony sulfide was used in ancient Egypt as a cosmetic for darkening the eyes.

Other uses

Some antimony salts are used as coating agents to remove microscopic bubbles that form on television screens. Antimony ions interact with oxygen, eliminating its tendency to form bubbles.

Antimony (III) sulfide is used in the heads of some safety matches. Antimony sulfide is also used to stabilize the coefficient of friction of materials used in automotive brake pads.

The ¹²⁴ Sb isotope, together with beryllium, is used as a neutron source, with an energy average of 24 keV. Furthermore, antimony is used as a catalyst in the production of plastics.

Risks

It is a brittle element, so a polluting dust from the environment can be produced during its handling. In workers exposed to antimony dust, dermatitis, renitis, inflammation of the upper respiratory tract and conjunctivitis have been observed.

Pneumoconiosis, sometimes combined with obstructive pulmonary changes, has been described after prolonged exposures.

Antimony trioxide can cause damage to heart function that can be fatal.

In people exposed to this element, the presence of transient pustular skin infections has been observed.

Continuous intake of low doses of this metal can cause diarrhea, vomiting and stomach ulcers. Also, the maximum tolerable concentration in air is 0.5 mg / m ³.

References

1. Shiver & Atkins. (2008). Inorganic chemistry. (Fourth edition). Mc Graw Hill.
2. Manny. (March 11, 2009). Yellow Antimony and Explosive Antimony. Recovered from: antimonyproperties.blogspot.com
3. Prof. Ernst Cohen and JC Van Den Bosch. (1914). The Allotropy of Antimony. Proceedings Royal Acad. Amsterdam. Vol. XVII.
4. Wikipedia. (2019). Antimony. Recovered from: en.wikipedia.org
5. Advameg, Inc. (2019). Antimony. Recovered from: chemistryexplained.com
6. Sable Mc'Oneal. (September 15, 2018). Chemistry: properties and application of Sb-Antimony. Recovered from: medium.com