Arsenic


Taylor Measel and Natalie Franzen
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1) Introduction to Arsenic:

Arsenic, or As, has an atomic number of 33 and is found in Group 15 on the periodic table. It is one of the most toxic, but also common, elements. It's organic and inorganic forms occur naturally throughout the earth, with inorganic being the most abundant and toxic. Inorganic arsenic is associated with other metals in igneous and sedimentary rock, and occurs in combo with other elements, especially oxygen, chlorine and sulfur. The organic forms often contain carbon and hydrogen. Arsenic has historically and still is well known as a poison, as the pure inorganic form is colorless and odorless. It carries negative, and even fatal, health risk upon ingestion to humans, though has proved to be a useful element in many ways, such as in preservatives, fertilizer, medicines, and technology. Arsenic has three allotropic forms: yellow, black and gray. The gray form is brittle and most common as its solid state.











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2) The History of Arsenic:

Arsenic has an interesting past. The word arsenic originally was derived from the Greek word “arsenikon”(yellow orpiment). Arsenic was commonly used for murder in the Middle Ages. Jabir, an alchemist, came up with a form of arsenic called arsenic trioxide in the 700’s. This was untraceable and perfect for murder. There was no odor, no taste, it was just white powder. People who got sick were often mistaken to have cholera. Another useful technique of arsenic was mixing it with bronze to help make alloys stronger. In 1250 Albertus Magnus isolated the element by heating the compound of arsenic with soap. However, in 1649, Schrödinger came up with two ways to arrange arsenic. By the 17th century, arsenic was well known, and was talked about in many textbooks. During the 18th, 19th and 20th century, arsenic was used as medicine. It was used as medicine again in 1910 when a biologist named Paul Ehrlich came up with a medicine conatining arsenic called salvarsan. This was said to have helped treat syphilis. In World War II, arsenic was used as a factor for embalming fluids. Women in the Victorian Age would use arsenic as a type of makeup and it whitened their faces. Arsenic has been used in medicine, but that technique is rare now. However, people in Africa still use for medication. Today this element is mostly used for glass making, pesticides, and electronics.





3) Ecplaying.jpgonomics of Arsenic:

Although Arsenic is extremely toxic, it has many uses in industries today. Most the arsenic produced in the United States is used to make wood preservative with chromated copper arsenate (This accounts for 90% of the Arsenic used in the U.S.). This is used in construction, railway, and utilities industries to protect outdoor wood from water damage and rot. Arsenic is also used to make certain types of glass and agricultural chemicals (such as insecticides and growth stimulants). Very high-purity arsenic is used to create the semiconductor gallium arsenide, that converts electric currents to laser light. The same compound is also used in LED lights and solar cells, and indium arsenide is used in laser lights and and infrared devices. The microchip industry uses a compound of Arsenic to create Arsine gas, or AsH3, an important dopine gas.

4) Health:

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Arsenic is one of the most toxic elements found on earth, and has a reputation across history and today as a deadly poison. However its inorganic bonds occur naturally and abundantly in small amounts in nature and can be taken in through food, water, air, and skin contact. While arsenic is essential in very small amounts for the diet, large amounts have serious side effects, and possible death. It irritates the stomach and intestines, and symptoms can be nausea, vomiting, diarrhea and the swelling of the liver. Over time, ingestion of arsenic produces damage to blood vessels, decreased production of red and white blood cells, a "pins and needles" sensation in the hands and feet, appetite and hair loss, abnormal heart beat, and small warts or corns on the palms of the hands and the soles of the feet (side picture). Direct contact with skin will produce redness and swelling. Consistent, high exposure to arsenic has a connection to certain cancers in the body. By swallowing arsenic there may be a higher risk of bladder, kidney, liver, and lung cancer (lung cancer is also linked to inhalation of arsenic in the air), and skin and lymphatic cancer have also been observed. Other risks with high exposure to arsenic include infertility and miscarriages in woman. There is also less resistance to infection, and brain and heart damage. With a very large intake or a long period of exposure, there is eventual death. The lethal dose of arsenic to humans can be 2 to 20 mg/kg body weight per day.






5) Environment:
mineral.jpgBelieve it or not, we are exposed to arsenic everyday. It's in the air, the water, the soil and even in our food. 1/3 of the arsenic comes from natural resources, like earth’s crust. The abundance in the earth’s crust is about 5 parts per million. Volcanoes are very important in producing natural arsenic as well. Arsenic is found in over 200 mineals. Infact, Wells that are deeply drilled into the ground may have high levels of arsenic. It is most commonly found in an inorganic mineral called arsenopyrite. It rarely occurs as an element. We mostly find it as a compound while mining. Some compounds may include arsenopyrite (mispickel), orpiment, and realgar. There can be manmade arsenic or "elemental arsenic." Usually, Arsenic is combined with charcoal. 70% of the man made arsenic is used as copper chrome arsenate. This is used to preserve wood. When making houses, the wood is often coated with it so the wood doesn’t rot. 22% is used for agriculture, for pesticides, as mentioned earlier. The remainder is used in glass making and medicine. Although the U.S. has arsenic, all of it is imported, there is none produced in the U.S. When we burn fossil fuels, this leads to a buildup of arsenic in the air, soil, and water which can be very hazardous. The concentration of arsenic in rocks vary. The arsenic from the rocks and the soild seep down into the underground water and is later pumped out and used for drinking water. The EPA set up a law in 2006 to protect 13 million people. They stated that all of the standard drinking water has to have a arsenic level of .010 parts per million. Arsenic can come in handy in our everyday lives, however, too much can be fatal.



6) Chemistry/Physics of Arsenic:


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Symbol: As
Atomic number: 33
Atomic mass: 74.9216
Density: 5.72g
Melting point: 814°C (1,500°F)
Column: 15
Row: 4

Type: Metalloid
Boiling point: 615 °C
Electron configuration: 1s2 2s22p6 3s23p23d10 4s24p3 or [ Ar ] 3d10 4s2 4p3
Strucrure: Rhombohedral
Isotope
Half Life
As-71
2.7 days
As-72
26.0 hours
As-73
80.3 days
As-74
17.8 days
As-75
Stable
As-76
26.3 hours
As-77
39.0 hours
As-79
9.0 minutes

    • Arsenic comes in 3 allotropic forms: yellow, black, and grey. The grey form is most stable but tarnishes when it reacts with oxygen. The grey form is the only metallic form.
    • The video below will give you a better idea of what arsenic trioxide looks like


7) Interesting Facts:

  • 77 million people in Bangladesh are and have been exposed to toxic levels of arsenic with contaminated groundwater. In the 1970's a campaign to get clean drinking water in the area backfired into a disaster when the tunnels that would deliver water to the country were dug into shallow layers of the ground that contained naturally-occurring arsenic. Many people have died or have heart disease and cancer. The World Health Organization has called it "the largest mass poisoning of a population in history."
* This video shows more on the news story.


8) Works Cited: