Cobalt Facts and Physical Properties

Cobalt Facts and Physical Properties Atomic Number: 27 Symbol: Co Atomic Weight: 58.9332 Discovery: George Brandt, circa 1735, maybe 1739 (Sweden) Electron Configuration: [Ar] 4s2 3d7 Word Origin: German Kobald: evil spirit or goblin; Greek cobalos: mine Isotopes: Twenty-six isotopes of cobalt ranging from Co-50 to Co-75. Co-59 is the only stable isotope. Properties Cobalt has a melting point of 1495Â °C, boiling point of 2870Â °C, specific gravity of 8.9 (20Â °C), with a valence of 2 or 3. Cobalt is a hard, brittle metal. It is similar in appearance to iron and nickel. Cobalt has a magnetic permeability around 2/3 that of iron. Cobalt is found as a mixture of two allotropes over a wide temperature range. The b-form is dominant at temperatures under 400Â °C, while the a-form predominates at higher temperatures. Uses Cobalt forms many useful alloys. It is alloyed with iron, nickel, and other metals to form Alnico, an alloy with exceptional magnetic strength. Cobalt, chromium, and tungsten may be alloyed to form Stellite, which is used for high-temperature, high-speed cutting tools and dies. Cobalt is used in magnet steels and stainless steels. It is used in electroplating because of its hardness and resistance to oxidation. Cobalt salts are used to impart permanent brilliant blue colors to glass, pottery, enamels, tiles, and porcelain. Cobalt is used to make Sevres and Thenards blue. A cobalt chloride solution is used to make a sympathetic ink. Cobalt is essential for nutrition in many animals. Cobalt-60 is an important gamma source, tracer, and radiotherapeutic agent. Sources: Cobalt is found in the minerals cobaltite, erythrite, and smaltite. It is commonly associated with ores of iron, nickel, silver, lead, and copper. Cobalt is also found in meteorites. Element Classification: Transition Metal Cobalt Physical Data Density (g/cc): 8.9 Melting Point (K): 1768 Boiling Point (K): 3143 Appearance: Hard, ductile, lustrous bluish-gray metal Atomic Radius (pm): 125 Atomic Volume (cc/mol): 6.7 Covalent Radius (pm): 116 Ionic Radius: 63 (3e) 72 (2e) Specific Heat (20Â °C J/g mol): 0.456 Fusion Heat (kJ/mol): 15.48 Evaporation Heat (kJ/mol): 389.1 Debye Temperature (K): 385.00 Pauling Negativity Number: 1.88 First Ionizing Energy (kJ/mol): 758.1 Oxidation States: 3, 2, 0, -1 Lattice Structure: Hexagonal Lattice Constant (Ã…): 2.510 CAS Registry Number: 7440-48-4 Cobalt Trivia Cobalt derived its name from German miners. They named cobalt ore after mischievous spirits called kobalds. Cobalt ores commonly contain the useful metals copper and nickel. The problem with cobalt ore is it usually contains arsenic as well. Attempts to smelt the copper and nickel typically failed and would often produce toxic arsenic oxide gases.The brilliant blue color cobalt gives to glass was originally attributed to bismuth. Bismuth is often found with cobalt. Cobalt was isolated by Swedish chemist, Georg Brandt who proved the coloring was due to cobalt.The isotope Co-60 is a strong gamma radiation source. It is used to sterilize food and medical supplies as well as radiation therapy in the treatment of cancer.Cobalt is a central atom in vitamin B-12.Cobalt is ferromagnetic. Cobalt magnets stay magnetic to the highest temperature of any other magnetic element.Cobalt has six oxidation states: 0, 1, 2, 3, 4, and 5. The most common oxidation states are 2 and 3.The oldest cobalt col ored glass was found in Egypt dated between 1550-1292 B.C. Cobalt has an abundance of 25 mg/kg (or parts per million) in the Earths crust.Cobalt has an abundance of 2 x 10-5 mg/L in sea water.Cobalt is used in alloys to increase temperature stability and decrease corrosion. References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Langes Handbook of Chemistry (1952), CRC Handbook of Chemistry Physics (18th Ed.) International Atomic Energy Agency ENSDF database (Oct 2010) Return to the Periodic Table

To whoose homecoming does the play refer essays

To whoose homecoming does the play refer essays To Whose Homecoming Does The Play Refer? In the play The Homecoming by Harold Pinter, a family deals with the unexpected return of the eldest son and his wife, Ruth, on a visit from America. The rest of the family were unaware that Teddy had taken a wife. The arrival had a profound effect on each member of the family who are an unusual group consisting of an aging father, his two sons and his younger brother. Because of this unexpected event we see the intricacies of the relationships of the family and how these develop and change. The homecoming does not necessarily bring about change in a good way if viewed as a whole. If certain characters are looked at individually though, we see many things that happen are positive for that person. The play would seem to centre around Teddy as he was the one returning home to his family. In fact, the attention is focused on Ruth. Maxs first reaction to her is abusive and he immediately calls Ruth a tart: Weve had a stinking pox-ridden slut in my house all night. This shows us how Max views women as he has never even set eyes on Ruth before this meeting. His words do not shock anyone and appear to be perfectly acceptable and normal. Even Teddy does not seem to surprised about this and although he does protest he is not particularly forceful. He seems to realise that there is no point in arguing with his father as he would not listen and I suspect that Teddy is used to his fathers ignorance and anti-female words. Ruth also does not try to defend herself or get upset. She is totally calm and surveys the scene silently with the same confidence she had expressed with Lenny the night before. From the very beginning of the play we are given an idea of their attitude to women. We learn that there is no woman in the household because Maxs wife Jessie had died. It later becomes clear that Lenny is a pimp and owns flats in whic...

CRJS310 U5IP Research Paper Example | Topics and Well Written Essays - 500 words

CRJS310 U5IP - Research Paper Example Recognising the signs of stalking is important in the following ways (Sheridan & Blaauw, 2004). It helps the victim to be aware and avoid falling prey to the attacker by taking caution early enough. Since stalking may range from the usually less discernible signs, being aware of such plans may help greatly in seeking help from the right channels quite early enough. It aids in making the office personnel entrusted in such issues of handling victims not to give a chance of loopholes to the advantage of the villain. Such loops may be created by ignorance information or underestimation by the personnel (Pathe, Mullen, & Purcell, 1999). ‘A stalking victim may be in the category of; ex-intimates, casual acquaintances and friends, professional contacts, work contacts, strangers and the famous’ (Kennedy, 2010, p. 33). Identifying the category of stalkers you are dealing with helps you greatly to attend to a stalking victim. It is of importance to listen to the concerns of the stalking victim and readily show concern to the grievances. This helps such a victim to feel comfortable in expressing their concerns (Lemon, 2012). Immediate and competent actions should be taken to curb additional harm to the victim. Every evidence put forward should in no way underestimated. The stalker should be warned and apprehended once they’ve been identified. This ensures the security of the victim from further harassment. Once a concern has been levelled by a victim, it is of great concern to provide security for such victims. This helps them to gather courage to report potential stalkers without fear of retaliatory attacks from them (Sheridan D. B., 2001). It is also important to note that some of the victims may not be genuine. This category may include stalkers who claim to be victims, some with delusions of being stalked, the previously stalked, the fictitious disorder and malingerer. This calls for extensive