Actinides (Actinide Series) Element Properties

At the bottom of the periodic table is a special group of metallic radioactive elements called actinides or actinoids. These elements, usually considered ranging from atomic number 89 to atomic number 103 on the periodic table, have interesting properties, and play a key role in nuclear chemistry. Location The modern periodic table has two rows of elements below the main body of the table. The actinides are the elements in the bottom of these two rows, while the top row is the lanthanide series. These two rows of elements are placed below the main table because they dont fit into the design without making the table confusing and very wide. However, these two rows of elements are metals, sometimes considered a subset of the transition metals group. In fact, the lanthanides and actinides are sometimes called the inner transition metals, referring to their properties and position on the table. Two ways of placing the lanthanides and actinides within a periodic table are including them in their corresponding rows with the transition metals, which makes the table wider, or ballooning them out, making a three-dimensional table. Elements There are 15 actinide elements. The electronic configurations of the actinides utilize the f sublevel, with the exception of lawrencium, a d-block element. Depending on your interpretation of the periodicity of the elements, the series begins with actinium or thorium, continuing to lawrencium. The usual list of elements in the actinide series is: Actinium (Ac)Thorium (Th)Protactinium (Pa)Uranium (U)Neptunium (Np)Plutonium (Pu)Americium (Am)Curium (Cm)Berkelium (Bk)Californium (Cf)Einsteinium (Es)Fermium (Fm)Mendelevium (Md)Nobelium (No)Lawrencium (Lr) Abundance The only two actinides found in appreciable quantities in the Earths crust are thorium and uranium. Small quantities of plutonium and neptunium are present in uranium orders. Actinium and protactinium occur as decay products of certain thorium and uranium isotopes. The other actinides are considered synthetic elements. If they occur naturally, it is part of a decay scheme of a heavier element. Common Properties Actinides share the following properties: All are radioactive. These elements have no stable isotopes.Actinides are highly electropositive.The metals tarnish readily in air. These elements are pyrophoric (spontaneously ignite in the air), particularly as finely divided powders.Actinides are very dense metals with distinctive structures. Numerous allotropes can be formed—plutonium has at least six allotropes. The exception is actinium, which has fewer crystalline phases.They react with boiling water or dilute acid to release hydrogen gas.Actinide metals tend to be fairly soft. Some can be cut with a knife.These elements are malleable and ductile.All the actinides are paramagnetic.All these elements are silver-colored metals that are solid at room temperature and pressure.Actinides combine directly with most nonmetals.The actinides successively fill the 5f sublevel. Many actinide metals have properties of both d block and f block elements.Actinides display several valence states, typically more than the lanthanides. Mos t are prone to hybridization.The actinides (An) may be prepared by reduction of AnF3  or AnF4  with vapors of Li, Mg, Ca, or Ba at 1100-1400 C. Uses For the most part, we dont often encounter these radioactive elements in daily life. Americium is found in smoke detectors. Thorium is found in gas mantles. Actinium is used in scientific and medical research as a neutron source, indicator, and gamma source. Actinides may be used as dopants to make glass and crystals luminescent. The bulk of actinide use goes to energy production and defense operations. The primary use of the actinide elements is as nuclear reactor fuel and in the production of nuclear weapons. The actinides are favored for these reactions because they readily undergo nuclear reactions, releasing incredible amounts of energy. If the conditions are right, the nuclear reactions can become chain reactions. Sources Fermi, E. Possible Production of Elements of Atomic Number Higher than 92.  Nature,  Vol. 133.Gray, Theodore .  The Elements: A Visual Exploration of Every Known Atom in the Universe. Black Dog Leventhal.Greenwood, Norman N. and Earnshaw, Alan. Chemistry of the Elements, 2nd edition. Butterworth-Heinemann.

High School Sports Be A Drastic Decision Essay - 1165 Words

Public high schools in the United States are responsible for predominantly educating children in the classroom. However, an education should be well rounded and teach students about multiple different aspects of life. Fitness education, physical education, and high school athletics are competitive. Public high schools hold the responsibility to offer as many sports as possible and to support as many students to succeed. Terminating high school sports would be a drastic decision. â€Å"One 2010 study by Betsey Stevenson, then at the University of Pennsylvania, found that, in a given state, increases in the number of girls playing high-school sports have historically generated higher college-attendance and employment rates among women. Another study, conducted by Columbia’s Margo Gardner, found that teenagers who participated in extracurriculars had higher college-graduation and voting rates, even after controlling for ethnicity, parental education, and other factors† (Ri pley, â€Å"The Case Against High School Sports†). However we cannot ignore the fact that high school sports require a large amount of tax dollars, attribute to lower academic rankings, and pressure youth to conform for organization regulations. â€Å"‘Sports are a big deal here,’ says Jenny.† (Ripley, â€Å"The Case Against High School Sports†) Jenny is a fifteen year old who moved to America from South Korea in 2011. She was quoted describing how America’s education system surprised her. In southern New Jersey she attendedShow MoreRelatedDrug Testing of High School Students1075 Words   |  5 PagesMandatory Drug Testing of High School Athletes Brandon had always wanted to play football for his high school team. 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An Analytical Free Essays

Does Lili Rose make a right choice in the story â€Å"Curly Red † by Joyce Carol Oates? Why or why not? Lili Rose the protagnist of the story ,†Curly Red†by Joyce Carol Oates depicts the tension between her and her father by stating †Daddy ? I had to do it. I did’nt have any choice. I’wondered if it was true,dont we always have choices. We will write a custom essay sample on An Analytical or any similar topic only for you Order Now †This quote focuses on the decisions Lili Rose had to made about the involvement of her brothers in the racist crime. She made the right decision following her consciousness rather than loyality of her family. She lived a guilt free life after confessing the crime of her brother and correcting the family mistake by suppurting the truth. Lili Rose did not conceal the truth from the society instead she amend the mistake. Her ethical nature and loyality to truth made her different from her family . She decides to live a guilt free life. She was not sorry about anything she did and was determined that if it again ahppens to her she would do it again. Lili betrayed her family by revealing the secretof the involvement of her brothers in the murder. She confessed by stating,†I said Mom? It was Leo and Mario. I saw them with the baseball bat. They were the ones†. Her mother reacted furiously after listening this which indicates that her anger was releasing in physical way. Lili provided justice to Jadro Filer who was innocent. She gave justice to his family by confessing the truth beside the loyality of her family. Lili’s father was assuaging his own guilt by supporting Jadro Filer’s family financially. Lili was against this and thought that life cannot be retained by money. lili’s parents try to protect leo and mario from the crime. lili followed her inner consciousness and told the truth which left her alone the wholelife. Lili Rose’s †love†towards her brothers changes into†hate† when she realizes the horrible nature of her brothers . This illustrates in the story when Lili states †Only years later would I wonder what leo and mario had done to me if they’d guessed all that i knew. † lili feels that it is her personal responsibility to tell the truth about their crime as she did not want to carry this guilt her whole life. Hence,Lili Rose followed her consciousness rather than her family and supported the truth . she made the right choice which however changed her life forever. Delete ReplyReply ForwardMovePrint Actions NextPrevious How to cite An Analytical, Papers

Children And Television Essay Example For Students

Children And Television Essay Children are vulnerable and easily swayed by everything around them. Parents try to do everything in their power to protect their children from unhealthy environments. They child-proof everything, but they dont realize that thousands of strangers enter the home everydaythrough the television. Television is in 98% of North American homes and the average Canadian child watches four hours of television every day. Most parents do not realize that their children are watching violence-ridden television programs and that by the age of 18 the average North American child will have viewed over 200,000 acts of television violence. Children should not be allowed to watch violent television programs because children are easily desensitized to violence, they are unable to distinguish reality and fantasy and they copy what they see on television. Children are very impressionable and are easily desensitized to the violence they see on television. Research has shown that young children are aroused b y aggressive scenes on television and show higher levels of emotion when watching aggressive programs than when watching passive programs. The arousal diminishes with repeated exposure to television and the violence no longer affects children. When people are no longer aroused by violence they become less responsive to human suffering and may not be as quick to help or may not intervene during an emergency. When there is a problem, arousal levels are high and quick action is taken but when arousal levels do no increase then people are not as concerned about the problem and may not jump in to solve it. Because society is becoming more aggressive, there will be more violent sociatal situations and if people do not take swift action and help because they are desenstiaed to the violence, many lives could be lost. Young children have trouble distinguishing between reality and fantasy. They cannot make objective evaluations, cannot form logical conclusions and cannot sort out relevant dat a about the things they see on television. They dont understand the difference between what is possible and what is actually probable. If a young child see someone on TV jumping off a mountain and landing on their feet, they believe that it is real becausw they saw it happen with their own eyes and do not have the capacity to believe otherwise. Children do not develop the capacity to distinguish reality and fantasy until their pre-school years and the distinction is not completely in place until the child is eight or nine years old. Children believe that what they see on television is real and they sometimes copy it. When children see acts of violence that go unpunished, they believe that the violent act is accepted in society and learn to imitate it. The movie The Kindergarten Cop is an example of a violent act that goes unpunished. In the movie which was gearded toward children, Arnold Schwarzenegger assults a child molester. He is then called into the principals office, expecting to get in trouble for fighting in front of the children he teaches. Instead, after a dramatic pause, the principal asks How did it feel to punch out that son of a bitch? Schwarzenegger is congratulated for his violent actions. If children see examples of unpunished violence like in Kindergarten Cop, they will believe that all violence is accepted and imitate it. One example, where children copied what they saw on television happened in 1958 when two boy were caught after they had commited a professional burglary by forcing the skylig ht. When questioned by the judge, the boys admitted that they had learned the method by watching a robbery commited on a television show. The only difference, they said, was that the burglers on the show didnt get caught. If television continues to show violence that is not penalized, then children will continue to copy what they have seen on TV. Parents who do not want their children copying the violence they see should be vigilant in monitoring the amount of TV their children are watching in addition to the type of programs. In the formative years, they should also explain to their children the difference between pretend and reality. For example, if the child sees someone getting shot on a TV program, the parent should point out that these are just actors pretending to get shot with a pretend gun. Frank discussions about the repercussions of real violence should also be discussed, with the focus on right and wrong behavior. This will help develop a sense of morality within the chi ld which will allow him or her to make more informed decisions. The hue and cry about reducing the amount of violence on TV has had little affect on programmers or producers. The best defense parents can mount against the cumulative affects of television violence is to clearly explain to their children what is acceptable behavior. If parents explain their expectations to their children, they will be better able to formulate their own opinion regarding violence within a strong moral framework rather than within a blurred and confused sense of television reality which glorifies violence and makes is seen acceptable. Autism EssayWords/ Pages : 1,769 / 24