Others include realgar, orpiment and enargite. Most arsenic is produced as a by-product of copper and lead refining. It can be obtained from arsenopyrite by heating, causing the arsenic to sublime and leave behind iron II sulfide. Help text not available for this section currently.
Elements and Periodic Table History. Arsenic was known to the ancient Egyptian, and is mentioned in one papyrus as a ways of gilding metals. He compiled his great work on the natural world in the s, during the Ming dynasty.
He noted the toxicity associated with arsenic compounds and mentioned their use as pesticides in rice fields. A more dangerous form of arsenic, called white arsenic, has also been long known. This was the trioxide, As 2 O 3 , and was a by-product of copper refining. When this was mixed with olive oil and heated it yielded arsenic metal itself. The discovery of the element arsenic is attributed to Albertus Magnus in the s.
Atomic data. Bond enthalpies. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom. Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey. Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk.
Recycling rate The percentage of a commodity which is recycled. Substitutability The availability of suitable substitutes for a given commodity. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Supply risk. Relative supply risk 7. Young's modulus A measure of the stiffness of a substance.
Shear modulus A measure of how difficult it is to deform a material. Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced. Listen to Arsenic Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry.
This week, poisons in paint, fireworks and aphrodisiacs, Napoleon's wallpaper and the whiff of garlic, what's the link? Here is Bea Perks. Mention arsenic to anyone even a chemist, the first word that is likely to come to mind is poison, it is of course a deadly poison, but its compounds also found or have been found in insecticides, colouring agents, wood preservatives, in animal feed, as a treatment for syphilis, and treatments for cancer, as a treatment for psoriasis, in fireworks and as a semiconductor.
Just may be as an aphrodisiac. Arsenic, atomic number 33 lies in between phosphorus and antimony in group 15, the so called Nitrogen group of the periodic table. Members of the group including of course nitrogen, along with arsenic, phosphorous, antimony and bismuth are particularly stable in compounds because they tend to form double or triple covalent bonds.
The property also leads to toxicity particularly evident in phosphorus, antimony and most notoriously, arsenic. When they react with certain chemicals in the body they create strong free radicals that are not easily processed by the liver where they accumulate. Arsenic is neither a metal nor a non-metal but instead joins a select but rather ill defined group of elements called the metalloids.
These are found in the periodic table along a diagonal line from Boron at the top left to round about polonium at the bottom right. Everything to the right of the line in the periodic table is a non-metal and everything to the left is a metal. The exact members of the group are open to debate but arsenic is always a member. Most metalloids occur in several forms or allotropes where one might seem metallic while another one seems non-metallic.
Carbon isn't a metalloid because despite the semiconductor properties of graphite all of its allotropes from graphite to diamond are non-metallic in character.
Arsenic gets its name from a Persian word for the yellow pigment now known as orpiment. For keen lexicographers apparently the Persian word in question Zarnikh was subsequently borrowed by the Greeks for their word arsenikon which means masculine or potent.
Orpiment or yellow arsenic trisulphide is a historical pigment identified in ancient Egyptian artefacts. On the pigment front they were hardly dare mentioned it, such a well worn tale, Napoleon's wallpaper just before his death is reported to have incorporated a so called Scheele's green which exuded an arsenic vapour when it got damp.
All well and good except that Napoleon also suffered from stomach ulcers, gastric cancer, tuberculosis, etc etc, so make of it what you will! Arsenic doesn't seem much like a metal in its so called yellow form, but it also has a grey form known tellingly as metallic arsenic. Yellow arsenic has a specific gravity of 1. Grey arsenic is the usual stable form with a melting point of degree Celsius. It is a very brittle semi-metallic solid, steel grey in colour that tarnishes readily in air.
It's rapidly oxidized to arsenous oxide which smells of garlic if you are brave enough to smell it when you heat it. In the days when deliberate arsenic poisoning remained a real threat and before the arrival of tests that could alert the authorities to its presence. Poisoning was some times diagnosed on the basis of a victim's garlic breath.
In a curious twist far more recently, researchers in India showed that eating 1 to 3 cloves of garlic a day could protect people from the arsenic poisoning associated with contaminated drinking water.
The reappearance of garlic is coincidental and the type of poisoning, acute deliberate poisoning versus unintentional long term poisoning by drinking water is very different. Arsenic levels in ground water are sometimes elevated as a result of erosion from local rocks. There's a particular problem in Bangladesh, rising arsenic levels there followed what was supposed to be an improvement to the water supply. Local populations used to get their drinking water from open sources like ponds.
But about 30 years ago they started getting water from wells. Well digging saw a marked decrease in water borne infections. By it was discovered that arsenic was present in these wells. The first symptoms found in people drinking arsenic contaminated water include pigmentation changes in the skin and skin thickening or hyperkeratosis.
After about 10 years drinking that water symptoms extend to skin and internal cancers. The World Health Organization report that arsenic in drinking water could end up causing between , to , deaths in Bangladesh from cancer. Arsenic levels appear to be lower in shallower, ground water or in much deeper aquifers and this knowledge should hopefully contribute to reducing the risks in future.
On a lighter note, I'm afraid there isn't much evidence despite its link with the Greek word for potent that arsenic is an aphrodisiac. It's a shame because it might have been rather useful if it was. An arsenic-based drug called Salvarsan was developed in by Nobel laureate Paul Ehrlich to treat the sexually transmitted disease syphilis.
Chemistry world's Bea perks on the science of element number 33, arsenic. And if you think arsenic is nasty, wait till you meet next week's element.
It sounds like a Doctor Who monster and in a number of ways this element does have a few properties that would make it suitable for any good, outer space sci-fi horror movie. For a start, like many space monsters it comes from slime. Every good monster must have a secret weapon and tellurium is no exception. It gives its enemies garlic breath. Really bad garlic breath. That was Peter Wothers who will be here to tell the tale of the smelly element tellurium on next week's Chemistry in its element.
I hope you can join us. I'm Chris Smith, thank you for listening and goodbye. Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.
Click here to view videos about Arsenic. Some properties of arsenic include: [3]. It requires pressures of 28 atm in order to phase change from a solid to a liquid , hence the higher temperature. Arsenic is emitted from various energy related sources.
It can be emitted from external combustion boilers , copper and zinc smelting , copper mining, uranium mining , and lead smelting. It may also arise from waste incineration and glass manufacturing. Emissions of arsenic from these sources is caused by the trace amount of arsenic in the fuels they use and the materials they process. The actual amount of arsenic emitted varies quite considerably, for instance the emissions of arsenic contained in coal may vary up to 4 orders of magnitude. Arsenic is relatively safe in its organic form bound to carbon , however it is extremely toxic in its inorganic form.
Inorganic arsenic is found in groundwater in high amounts in some countries around the world, or in the air as pollution. People may be exposed to arsenic through contaminated water. This can be a problem if water with arsenic is drank, used for food preparation, or raising crops. Naphthalene , a common ingredient in mothballs , also sublimes easily. Arsenic can also sublime at high temperatures.
Sublimation requires additional energy and is an endothermic change. The enthalpy of sublimation can be calculated as the enthalpy of fusion plus the enthalpy of vaporization. Other substances, such as ammonium chloride , appear to sublime because of chemical reactions.
When heated, it decomposes into hydrogen chloride and ammonia, which quickly react to reform ammonium chloride. Sublimation is a technique used by chemists to purify compounds. Typically a solid is placed in a vessel which is then heated under vacuum. Under this reduced pressure the solid volatilizes and condenses as a purified compound on a cooled surface, leaving the non- volatile residue impurities behind.
This cooled surface often takes the form of a cold finger. Once heating ceases and the vacuum is released, the purified compound can be collected from the cold surface. Frost-free freezers work by having a fan and air circulation inside the freezer. The sub-zero temperature combined with the air circulation that keeps the air arid significantly accelerates the sublimation process. This keeps freezer walls and shelves free of ice, although ice-cubes will continually sublimate. Dye sublimation is also often used in colour printing on a variety of substrates , including paper.
A small heater is used to vaporize the solid dye material, which then solidifies upon the paper.
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