Monday, 19 November 2012

Elements and their origins

Lithium was discovered by Johan August Arfvedson at 1817 in Stockholm, Sweden. Origin of name: from the Greek word "lithos" meaning "stone", apparently because it was discovered from a mineral source whereas the other two common Group 1 elements, sodium and potassium, were discovered from plant sources..
The mineral petalite (which contains lithium) was discovered by the Brazilian scientist José Bonifácio de Andrada e Silva towards the end of the 18th century while visiting Sweden. Lithium was discovered by Johan August Arfvedson in 1817 during an analysis of petalite ore, an ore now recognised to be LiAl(Si2O5)2, taken from the Swedish island of Utö. Arfvedson subsequently discovered lithium in the minerals spodumene and lepidolite. C.G. Gmelin observed in 1818 that lithium salts colour flames bright red. Neither Gmelin nor Arfvedson were able to isolate the element itself from lithium salts, for example in attempted reductions by heating the oxide with iron or carbon.
The first isolation of elemental lithium was achieved later by W.T. Brande and Sir Humphrey Davy by the electrolysis of lithium oxide. In 1855, Bunsen and Mattiessen isolated larger quantities of the metal by electrolysis of lithium chloride.
In 1923 the first commercial production of lithium metal was achieved by Metallgesellschaft AG in Germany using the electrolysis of a molten mixture of lithium chloride and potassium chloride, exploiting a suggestion made by Guntz in 1893

Uses of Lithium
  • Lithium can be used as a coolant due to its high specific heat capacity.
  • Compounds of lithium give fireworks and flares a red color.
  • LiOH (lithium hydroxide) is used to make lithium soaps. These soaps are used to manufacture lubricating greases.
  • Lithium can be used in disposable and rechargeable batteries. Some rechargeable batteries include the lithium-ion battery and the lithium iron phosphate battery.
  • Lithium niobate is used to make cell phone.
  • Lithium is used to absorb neutrons in nuclear fusion.
  • Lithium can be combined with other metals (usually aluminum, cadmium, copper or manganese) to make airplane parts.
  • Lithium hydroxide and lithium peroxide are used to purify air in submarines and on spacecraft. Lithium peroxide is fantastic as it reacts with carbon dioxide to produce oxygen.
  • One of the most important uses of lithium is in the treatment of bipolar disorder and depression. Salts of lithium (such as lithium carbonate and lithium citrate) are mood stabilizers.
  • Lithium can be used in focal lenses for telescopes and common spectacles.
  • Lithium chloride and lithium bromide are effective desiccant. A desiccant is a substances that keeps something (usually a container) dry by absorbing (or adsorbing) water molecules.
  • Lithium, and its hydrides, are used as high energy additives in rocket propellants.


Beryllium was discovered by Nicholas Louis Vauquelin (1763-1829) at 1797 in France. Origin of name: from the Greek word "beryllos" meaning "beryl".
Emeralds and beryl were both known to early Egyptians but it was not realised until the end of the 18th century that they are the same mineral, now called beryllium aluminium silicate: [Be3Al2(SiO3)6]. The element was recognised by M.-L. Vauquelin in 1798 in beryl and emeralds. The metal was isolated much later on in 1828 by Friederich Wöhler (and independently by A.-A.B. Bussy) by the action of potassium on BeCl2 in a platinum crucible.
Beryllium is a Group 2 (IIA) element. It is a metal and has a high melting point. At ordinary temperatures, beryllium resists oxidation in air. Beryllium compounds are very toxic. Its ability to scratch glass is probably due to the formation of a thin layer of the oxide. Aquamarine and emerald are precious forms of the mineral beryl, [Be3Al2(SiO3)6].

Uses of Beryllium
  • Probably the most important use of beryllium is in radiation windows for X-ray tubes. Beryllium is ideal for this use as it has a very low absorption of X-rays.
  • Beryllium is used in the pipes of many high-energy particle physics collision experiments (such as the Large Hadron Collider). The stiffness of the metal allows a powerful vacuum to be created.
  • Beryllium is used as a lightweight component of military equipment and in the aerospace industry. It is used in high-speed aircraft, missiles, space vehicles and communication satellites.
  • It is one component of metal springs, non-sparking tools and electrical contacts.
  • Naval personnel use beryllium tools when working on or near naval mines. Beryllium is non-magnetic and most naval mines detonate when they come into contact with something magnetic.
  • Beryllium is used in the design of nuclear weapons. It is used as the outer layer of the pit in the primary stage. It is an excellent pusher for implosion and is very good at at reflecting neutrons.
  • The low weight and high rigidity of beryllium makes it perfect for use in high-frequency speaker drivers.
  • Beryllium oxide is an excellent heat conductor. Therefore, it is used as an insulator base plate in high-power transistors in RF transmitters for telecommunication purposes.
  • Beryllium mirrors can be used in telescopes.

Isolation: beryllium metal is available commercially and so would never normally be made in the laboratory. Its extraction from ores is complex. The mineral beryl, [Be3Al2(SiO3)6] is the most important source of beryllium. It is roasted with sodimu hexafluorosilicate, Na2SiF6, at 700°C to form beryllium fluoride. This is water soluble and the beryllium may be precipitated as the hydroxide Be(OH)2 by adjustment of the pH to 12.
Pure beryllium may be obtained by electrolysis of molten BeCl2 containing some NaCl. The salt is added since the molten BeCl2 conducts very poorly. Another method involves the reduction of beryllium fluoride with magnesium at 1300°C.



Boron was discovered by Sir Humphrey Davy, Joseph-Louis Gay-Lussac, L.J. Th&�nard at 1808 in England, France. Origin of name: from the Arabic word "buraq" and the Persian word "burah"
Boron compounds have been known for thousands of years, but the element was not isolated until 1808 by Sir Humphry Davy, Joseph-Louis Gay-Lussac (1778-1850) and Louis Jaques Thenard (1777-1857). This was accomplished through the reaction of boric acid (H3BO3) with potassium.

Boron is a Group 13 element that has properties which are borderline between metals and non-metals (semimetallic). It is a semiconductor rather than a metallic conductor. Chemically it is closer to silicon than to aluminium, gallium, indium, and thallium.

Uses of Boron
  • Much boron is made into sodium tetraborate which is used to insulate fiberglass. It is also used in many cleaning products- detergents and bleaches.
  • Most boron is used to produce glass and ceramics. Borosilicate glass has a fantastic resistance to thermal shock (sudden changes in temperature which causes glass to break).
  • Boron filaments are used as light but high-strength materials for aerospace structures. They are also used to produce some golf clubs and fishing rods.
  • Boron carbide shields can be used as control rods in nuclear reactors. This stops a nuclear reactor getting out of control. Boron carbide is also used in bulletproof vests and in tank armor.
  • Metal borides are very strong and are often coated onto a substance to increase its hardness.
  • Boron is a part of a neodynium magnet, the strongest type of permanent magnet. These magnets are used in MRI (Magnetic Resonance Imaging) machines, CD and DVD players, cell phones, timer switches and more.
  • Boric acid is sometimes used as an insecticide against ants, fleas and cockroaches.
  • Sodium borate can be used as a fire retardant in plastics and rubber.

Carbon
Classification: Carbon is a nonmetal
Color: black (graphite), transparent (diamond)
Atomic weight: 12.011
State: solid
Melting point: 3550 oC, 3823 K
Electrons:6
Protons:6
Neutrons in most abundant isotope:6

Interesting Facts about Carbon

  • About 20% of the weight of living organisms is carbon.
  • More compounds are known which contain carbon than don’t.
  • Diamond is an excellent abrasive because it is the hardest common material and it also has the highest thermal conductivity. It can grind down any substance, while the heat generated by friction is swiftly conducted away.
  • The carbon atoms in your body were all once part of the carbon dioxide fraction of the atmosphere.
  • Graphene is the thinnest, strongest material ever known.
  • Graphene is made of 2-dimensional atomic crystals, the first time such structures have ever been seen.
  • The graphite in a typical mechanical pencil has a diameter of 0.7 mm. This is equal to 2 million layers of graphene.
  • Car tires are black because they are about 30% carbon black, which is added to rubber to strengthen it. The carbon black also helps protect against UV damage to the tires.(8)
  • Carbon is made within stars when they burn helium in nuclear fusion reactions. Carbon is part of the ‘ash’ formed by helium burning.
  • Carbon undergoes nuclear fusion reactions in heavy stars to make neon, magnesium and oxygen.
  • Carbon is the fourth most abundant element in the universe.
  •  
    Carbon as charcoal, soot and coal has been used since prehistoric times. Carbon as diamond has also been known since very ancient times. The recognition that soot (amorphous carbon), graphite (another form of carbon) and diamond are all forms of carbon.
    A fourth form, buckminsterfullerene, formula C60, whose framework is reminiscent of the seams in an Association Football ("soccer") ball, is the subject of considerable interest at present and was only discovered a few years ago in work involving Harry Kroto, a Sheffield graduate.

    Nitrogen

    Nitrogen was discovered by the Scottish physician Daniel Rutherford in 1772. It is the fifth most abundant element in the universe and makes up about 78% of the earth's atmosphere, which contains an estimated 4,000 trillion tons of the gas. Nitrogen is obtained from liquefied air through a process known as fractional distillation.
    The largest use of nitrogen is for the production of ammonia (NH3). Large amounts of nitrogen are combined with hydrogen to produce ammonia in a method known as the Haber process. Large amounts of ammonia are then used to create fertilizers, explosives and, through a process known as the Ostwald process, nitric acid (HNO3).
    Nitrogen gas is largely inert and is used as a protective shield in the semiconductor industry and during certain types of welding and soldering operations. Oil companies use high pressure nitrogen to help force crude oil to the surface. Liquid nitrogen is an inexpensive cryogenic liquid used for refrigeration, preservation of biological samples and for low temperature scientific experimentation.
     
    Atomic Number: 7
    Atomic Weight: 14.0067
    Melting Point: 63.15 K (-210.00°C or -346.00°F)
    Boiling Point: 77.36 K (-195.79°C or -320.44°F)
    Density: 0.0012506 grams per cubic centimeter
    Phase at Room Temperature: Gas
    Element Classification: Non-metal

    Facts
    1.You breathe oxygen, yet air is mostly nitrogen. You need nitrogen to live and encounter it in the foods you eat and in many common
    2.Nitrogen is odorless, tasteless, and colorless.
    3.Nitrogen gas (N2) makes up 78.1% of the volume of the Earth's air.
    4.Nitrogen is responsible for the orange-red, blue-green, blue-violet, and deep violet colors of the aurora.
    5.Nitrogen gas is relatively inert, but soil bacteria can 'fix' nitrogen into a form that plants and animals can use to make amino acids and proteins.




    http://chemistry.about.com/od/elementfacts/a/nitrogenfacts.htm
    http://education.jlab.org/itselemental/ele007.html
    http://www.chemicool.com/elements/carbon.html
    http://www.webelements.com/beryllium/
    http://wanttoknowit.com/uses-of-beryllium/
    http://wanttoknowit.com/uses-of-lithium/
    http://www.webelements.com/lithium/
    http://wanttoknowit.com/uses-of-boron/

    Wednesday, 17 October 2012

    Emergency Contraception

    Emergency Contraception can prevent an unplanned pregnancy in the following situations:
    • No contraception was used
    • Missed birth control pills, patch, or ring
    • The condom slipped, broke, or leaked
    • The diaphragm or cervical cap is dislodged during sexual intercourse or was removed too early
    • Error in the calculation of the fertility period
    • Non-consensual sexual intercourse (sexual assault)
    Unlike other forms of contraception, emergency contraception (EC) can be used AFTER intercourse to prevent pregnancy. As the name suggests, emergency contraception is not something you want to rely on. This is a last chance contraception, and is sometimes called the “morning-after” pill. EC is a simple and safe way to prevent pregnancy.

    How it works
    EC, which is successful in preventing about three out of every four pregnancies that would have happened, works by delaying/preventing ovulation and can be taken up to 5 days after sex. Emergency contraceptives work by delaying or inhibiting the release of an egg (ovulation), altering the luteal phase length, and also possibly inhibiting the implantation of a fertilized egg. In the unlikely event that implantation does occur, EC does not interrupt the pregnancy or put the fetus at risk. However the sooner it is taken, the better it works.

    Another contraception called the copper intrauterine device (copper IUD) can also be used as emergency contraception up to 7 days after sex.

    http://www.sexualityandu.ca/birth-control/emergency-contraception-morning-after-pill

    Reproductive Technology

    Selective Reproduction

    http://www.theglobeandmail.com/life/parenting/unnatural-selection-is-evolving-reproductive-technology-ushering-in-a-new-age-of-eugenics/article1357885/?page=all


    Tuesday, 16 October 2012



    Apache Girl's Rite of Passage

    http://video.nationalgeographic.com/video/places/countries-places/united-states/us-apachegirl-pp/

    Initiation into womanhood

    Female initiation in South Africa can take on the form of either communal ceremonies or individual occasions. The most common communal ceremonies are those of the Venda vusha and domba, the Swazi reed dance and the Ndebele and Pedi bojale. The Zulu, Xhosa and other Nguni cultures (except the Ndebele) all have ceremonies that are more individual - with initiation taking place as each individual reaches puberty.
    With the onset of her first menarche cycle, a girl has to attend these initiation ceremonies. There she will be instructed in matters relating to sexual behaviour, tribal etiquette, wifely duties, married life and agriculture. The teaching of these matters is left in the hands of the most senior women in the village, as the custodians of tradition.
    Unlike the boys' initiation, which takes place outside in the field, the girls are usually housed in a special hut built for the occasion. These huts are situated in or near the chief's kraal. During this period the girls are secluded, sometimes smeared with white or ochre clay, and forbidden to speak with any male person. Strict dietary rules exist during this time and the girls endure almost merciless discipline.
    After the initiation period the girls receive new clothes from their mothers, shave off their hair and receive new names signifying their adult status. Unlike the greater part of Africa, female circumcision and clitoridectomy (female genital mutilation) is not practised in any South African culture. The initiates pass from childhood into adulthood with dignity and self-respect

    http://myfundi.co.za/e/Initiation_cycles_of_traditional_South_African_cultures

    Cree tribe

    Adolescence is the time of learning and preparation. Anne Cameron in her book Child of Her People describes preparations for girls in puberty in the Cree tribe. Since they turn 8, 9 they spend a part of each day with a specially selected Grandma representing the elders. She teaches them the origin story of the tribe, the story of First Woman, First Mother and the origins of Mother Earth. She teaches them what it means to become a woman, about changes in the body and the development of the psyche. Girls learn self-defence and practice it on the tribe’s boys. They gain knowledge about herbs soothing pain and preventing pregnancy. When they are finally ready, they spend time alone, in cleansing lodges. Only after two years of such preparation they are accepted into the tribe as women. They are perceived as those becoming Mother Earth, fertile, capable of creating and giving life.

    http://www.miesiaczka.com/index.php?option=com_content&view=article&id=77%3Arituals-for-girls-in-different-cultures&catid=5%3A1-miesiaczka&Itemid=42

    Bali Indonesia


    In Bali it is a tradition to file the upper canines even with the upper incisors. The Bali people believe this ritual helps to remove any forces of evil around the person as they believe the teeth to be symbols of jealousy, lust, greed, anger, confusion and insobriety. They believe that filing the teeth takes the evil traits away and makes the person more beautiful while at the same time ushering them into adulthood. The tooth filing ceremony is conducted by the Brahmin or priest whenever possible and is conducted under very stringent conditions, including the time of the ceremony, the tools used and even the person who is undergoing the ritual being kept isolated the day before the ceremony. The adolescents who have their teeth filed are well aware of the significance of the ceremony and refuse to cry out.



    http://akorra.com/2010/10/10/top-10-odd-puberty-rituals/

    Barabaig Culture of East Africa


    Among the many different cultures of the world that have rites of passage for young men transitioning to adulthood are the Barabaig cattle herding tribe of East Africa. These people believe that shaving the boy’s heads and cutting them down to the bone from ear to ear in three deep horizontal cuts would make them into men. The resulting scar, called a ‘gar’, is a symbol of manhood and the boys who have it wear it with pride



    http://akorra.com/2010/10/10/top-10-odd-puberty-rituals/

    Female Puberty Rituals Around the World


    Most cultures mark the rites of passage in life with special ceremonies, observations or events. The first of these is usually an event for the naming of the child, followed for girls usually by a rite marking the transition to adulthood.

    Customs vary throughout Africa according to region, nation and tribe. Villages in Ghana separate girls for several weeks from the rest of the village once they have their first period. During this time, girls are instructed in sex education and social mores regarding courtship and nonromantic relationships with males. Then a village-wide ceremony and celebration takes place, presenting the adolescent girls to the community.

    Rites have significance beyond just honoring or acknowledging the change in the girl's life. Some cultures use this as a chance to teach ethics and sexual morality to girls, or to choose a mate for the girl. A Brazilian tribe (Urubu-Kaapor) crops a girl's hair at her first menstruation and separates her from the village for fasting and education. She can't be married until her hair has grown back to shoulder-length, giving her time in the community to develop into an adult.

    http://science.howstuffworks.com/environmental/life/human-biology/female-puberty6.htm