Xenon :: essays research papers

Xenon Xenon is element number 54 on the periodic table of the elements. It has a mass of roughly 131 atomic mass units. There are 77 neutrons and 54 protons in the nucleus of the atom. The symbol for xenon is Xe and it belongs to the family of elements called the noble gases. It is called a noble gas because the valance shell of one atom contains a full shell. Xenon is one of the most stable elements on the table. The 54 electrons are arranged, so that there are 2 in the 1st shell, 8 in the 2nd, 18 in the 3rd, 18 in the 4th and lastly 8 in the 5th shell. The melting and boiling points of xenon are extremely low. They are -111 °C and -107 °C respectively.   Ã‚  Ã‚  Ã‚  Ã‚  Xenon and most of the other noble gases were discovered by Sir William Ramsey and M.W. Travers from England in 1898. The two scientists discovered it mistakenly while experimenting with crude krypton, another noble gas. They were separating the elements in the crude krypton through a process called fractional distillation. In fractional distillation, the process separates two elements that have different boiling points. Basic-ally, when a sample is heated, the faster element leaves first, leaving the second element behind. Krypton was known to have a boiling point at a temperature that is lower than xenon. So the scientists could predict that heating the mixture would leave krypton in the container, while the faster boiling xenon leaving it. After the two scientists separated krypton and xenon, they identified it as a new element through the emission spectrum of the gas.   Ã‚  Ã‚  Ã‚  Ã‚  Xenon is used heavily in light bulbs. Many of the bulbs in camera flashes have xenon in them, because they can be used over 10,000 times without burning out, as well as producing a good balance of all colors. Xenon is also used in medical purposes. Local anesthesia is made up of 20% oxygen and 80% xenon. Xenon also can be injected or breathed into the body to give clearer M.R.I.'s or X-rays. In addition to the uses above, xenon is also in movie projector lamps, advertising lights, and bubble chambers, Bubble chambers are devices used by physicists that are used to detect nuclear radiation. The element is very chemically stable and unradioactive and is generally not harmful to man. Xenon is also nonflammable. It is only when it combines with other elements that xenon becomes hazardous. Xenon compounds are highly radioactive. This element accounts for a very minimal amount of the earth's crust. Only 3x10-9% of the earth contains xenon.

Do Not Go Gentle to That Good Night by Dylan Thomas Essay

Dylan Thomas was a well-known poet and writer whose poems were very famous, such as â€Å"And Death Shall Have No Dominion† and â€Å"The Play for Voice.† He was born on 27 October 1914, and he died on 9 November 1953. He was very popular in his lifetime, and he is still known by his works after his death. One of his works that I think is the most significant poem is â€Å"Do Not Go Gentle into That Good Night.† This work had been published about two years before his death – 1951, and it is also a part of the collection In Country Sleep. Dylan used the poem to express his feeling while his father was losing health and strength, encouraging his father to hold on to life. The theme of this poem is death. At the first line of the poem, â€Å"Do not go gentle into that good night,† he wants to tell the unknown listeners not to go into that good night. We can easily find a poetic device of metaphor when he used the word night for death. We also have an extended metaphor in which day is life and night is death. The first line is also the title of the poem, repeated four times throughout the poem. The next two lines are â€Å"Old age should burn and rave at close of day/ Rage, rage against the dying of the light.† In the second line, we can see what the poet wants to show us about how the elderly should fight death with their remaining health. In addition, when he says â€Å"Rage, rage against the dying of the light,† he wants to clearly confirm that this is the processing of the age – the death of old age. The first stanza is the thesis statement of the poem about aging and death. The first line of second stanza â€Å"Though wise men at their end know dark is right,† the metaphor of darkness is continually used; dark represents death. The meaning of this sentence is the clever men think that we are all going to die – it’s totally a natural process. However, at the second line â€Å"Because their words had forked no lighting they / Do not go gentle into that good night.† This sentence has an implication. The â€Å"word† in this line is the action of the clever people. The poet shows the unknown listener that though the clever men know that the death of aging is natural, they still try to fight it; they â€Å"do not go gentle to that good night.† This idea is continually developed in the next two stanzas: â€Å"The wild men who caught and sang the sun in flight grieved it on its way† and â€Å"the grave men who see with blinding sight.† They still fight against the dying of light – the death of aging. In the final stanza, â€Å"And you, my father, there on the sad height,† we know the unknown listener is the poet’s father, and he is dying. The poet by this poem, tries to beg and encourage his father to fight against the â€Å"dying of the light.† The speaker ends the poem by two lines: â€Å"Do not go gentle to that good night / Rage, rage against the dying of the light.† These are also the two lines that were repeated throughout the poem. This poem is one of the famous poems in Dylan Thomas’s collection. The poem not only is an encouragement that tells us not give up but fight against the dying of aging, but also he wants to tell his father not go to the darkness – â€Å"Do not go gentle to the good night†. Work Cite Shmoop Editorial Team. â€Å"Do Not Go Gentle into That Good Night: Stanza 6 Summary† Shmoop.com. Shmoop University, Inc., 11 Nov. 2008. Web. 5 Feb. 2013

Negative Slope and Negative Correlation

In mathematics, the slope of a line (m) describes how rapidly or slowly change is occurring and in which direction, whether positive or negative. Linear functions—those whose graph is a straight line—have four possible types of slope: positive, negative, zero, and undefined.  A function with a positive slope is represented by a line that goes up from left to right, while a function with a negative slope is represented by a line that goes down from left to right. A function with zero slope is represented by a horizontal line, and a function with an undefined slope is represented by a vertical line. Slope is usually expressed as an absolute value. A positive value indicates a positive slope, while a negative value indicates a negative slope. In the function y 3x, for example, the slope is positive 3, the coefficient of x. In statistics, a graph with a negative slope represents a negative correlation between two variables. This means that as one variable increases, the other decreases and vice versa. Negative correlation represents a significant relationship between the variables x and y, which, depending on what they are modeling, can be understood as input and output, or cause and effect. How to Find Slope Negative slope is calculated just like any other type of slope. You can find it by dividing the rise of two points (the difference along the vertical or y-axis) by the run (the difference along the x-axis). Just remember that the rise is really a fall, so the resulting number will be negative. The formula for the slope can be expressed as follows: m (y2 - y1) / (x2 - x1) Once you graph the line, youll see that the slope is negative because the line goes down from left to right. Even without drawing a graph, you will be able to see that the slope is negative simply by calculating m using the values given for the two points. For example, suppose the slope of a line that contains the two points (2,-1) and (1,1) is: m [1 - (-1)] / (1 - 2) m (1 1) / -1 m 2 / -1 m -2 A slope of -2 means that for every positive change in x, there will be twice as much negative change in y. Negative Slope Negative Correlation A negative slope demonstrates a negative correlation between the following: Variables x and yInput and outputIndependent variable and dependent variableCause and effect Negative correlation occurs when the two variables of a function move in opposite directions. As the value of x increases, the value of y decreases. Likewise, as the value of x decreases, the value of y increases. Negative correlation, then, indicates a clear relationship between the variables, meaning one affects the other in a meaningful way. In a scientific experiment, a negative correlation would show that an increase in the independent variable (the one manipulated by the researcher) would cause a decrease in the dependent variable (the one measured by the researcher). For example, a scientist might find that as predators are introduced into an environment, the number of prey gets smaller. In other words, there is a negative correlation between number of predators and number of prey. Real-World Examples A simple example of negative slope in the real world is going down a hill. The farther you travel, the farther down you drop. This can be represented as a mathematical function where x equals the distance traveled and y equals the elevation. Other examples of negative slope demonstrate the relationship between two variables might include: Mr. Nguyen drinks caffeinated coffee two hours before his bedtime. The more cups of coffee he drinks (input), the fewer hours he will sleep (output). Aisha is purchasing a plane ticket. The fewer days between the purchase date and the departure date (input), the more money Aisha will have to spend on airfare (output). John is spending some of the money from his last paycheck on presents for his children. The more money John spends (input), the less money he will have in his bank account (output). Mike has an exam at the end of the week. Unfortunately, he would rather spend his time watching sports on TV than studying for the test. The more time Mike spends watching TV (input), the lower Mikes score will be on the exam (output). (In contrast, the relationship between time spent studying and exam score would be represented by a positive correlation since an increase in studying would lead to a higher score.)