Arsenic Essays (3685 words) - Arsenic, Toxicology, Oxoanions

Arsenic Element 33: Arsenic Abstract Arsenic is element 33 on the periodic table and is in Group 15. Arsenic is obviously an extremely poisonous element; however, some people have found arsenic to have a restorative effect on them. Chemically, arsenic is a metalloid. Two common forms of arsenic are gray and yellow. (see Figure 1-A) Element 33 has an atomic weight of 74.9216 and the chemical symbol of As. It boils at 613?C, melts at 817?C, and has a density of 5.72. (see Figure 2-A) The element has been known for centuries and can be easily obtained from ores such as arsenopyrite (FeAsS), realgar (As2S2), orpiment (As2S3), and arsenic trioxide (As2O3). There are many uses for arsenic. Among them is in the manufacturing of glass to eliminate the air bubbles and the green color caused by contaminated iron compounds. Arsenic is also added to materials such as lead and copper alloys to increase the strength and better the corrosion resistance. Although it is well known that arsenic is often used in tales (both true and other wise) as a killing agent, arsenic has been used as a curative as well. Before penicillin was introduced, arsenic played a significant role in the treatment of syphilis. Other good uses for element 33 are as insecticides and semiconductors. Gallium arsenide (GaAs) is a known semiconductor that is also used as a laser material. A good test for the detection of arsenic is the Marsh test, invented by James Marsh, an English chemist. Introduction Arsenic is a rather notorious element. Mystery lovers know it as the poison and in the past, it has been one of the favored choices of criminals. (Bodin and Cheinisse 1970) Arsenic compounds have been known in the world since the 4th century BC, though it wasn't described as an element until 1649. The ancient Romans knew of arsenic because it is a by-product of several ores they used: copper, zinc, tin, lead, and gold. (Schroeder 1974) Arsenic has many uses throughout the world. China is the largest producer of arsenic metal and arsenic trioxide. The United States is the largest consumer of the product, according to 1996 statistics. In fact, the United States attributed to about two-thirds of the world's demand. All of the arsenic required by the United States was imported. America had ceased the production of arsenic since 1985. Arsenic can be prepared in its pure form by heating arsenopyrite. It can also be found as by-products of other ores during smelting. (Edelstein 1996) Many people, when they think of arsenic, think of the element as a deadly and dangerous poison. And so it is. However, it is rarely come upon nowadays in clinical practice. Inorganic arsenicals are more likely to cause poisoning then arsenic derived organically. Arsenic is often used in products such as weed killers, insecticides, and rodenticides. Ingestion of any of these can cause severe poisoning. Most of the toxic effects of arsenic are on the digestive system, such as burning gastroenteritis. It can also cause hypotension and circulatory collapse in the cardiovascular system, and headaches and weak muscles in the nervous system. Victims of arsenic poisoning may also experience blood in their urine. Of course there are treatments for arsenic poisoning, but it is imperative to first make sure that arsenic is the cause of the poisoning because the treatment can be just as hazardous. (Matthew and Lawson 1970) Element 33, otherwise known as arsenic, is arguably one of the most well known elements in the world. At the same time, its properties and uses are considerably less known. Arsenic is the 20th most common naturally occurring element. It is present in all humans and is an easily obtainable poison. This element is also used in the production of ceramics, enamels, paint, wallpaper, glass, insecticides, pesticides, and rat poisons. (Turkington 1994) Arsenic also strengthens lead in batteries and improves copper alloys' resistance to corrosion. (Edelstein 1996) The electron configuration of arsenic is 2-8-18-5. (see Figure 3-A) (Web Elements 1998) In addition, it is a metalloid, meaning that it has characteristics of both metals and nonmetals. There are two valence states for arsenic: the pentavalent form and trivalent form. The pentavalent for is generally nontoxic and is organic. Though it seldom causes habitual poisoning,