Molecular Geometry Introduction

Molecular geometry or molecular structure is the three-dimensional arrangement of atoms within a molecule. It is important to be able to predict and understand the molecular structure of a molecule because many of the properties of a substance are determined by its geometry. Examples of these properties include polarity, magnetism, phase, color, and chemical reactivity. Molecular geometry may also be used to predict biological activity, to design drugs or decipher the function of a molecule. The Valence Shell, Bonding Pairs, and VSEPR Model The three-dimensional structure of a molecule is determined by its valence electrons, not its nucleus or the other electrons in the atoms. The outermost electrons of an atom are its valence electrons. The valence electrons are the electrons that are most often involved in forming bonds and making molecules. Pairs of electrons are shared between atoms in a molecule and hold the atoms together. These pairs are called bonding pairs. One way to predict the way electrons within atoms will repel each other is to apply the VSEPR (valence-shell electron-pair repulsion) model. VSEPR can be used to determine a molecules general geometry. Predicting Molecular Geometry Here is a chart that describes the usual geometry for molecules based on their bonding behavior. To use this key, first draw out the Lewis structure for a molecule. Count how many electron pairs are present, including both bonding pairs and lone pairs. Treat both double and triple bonds as if they were single electron pairs. A is used to represent the central atom. B indicates atoms surrounding A. E indicates the number of lone electron pairs. Bond angles are predicted in the following order: lone pair versus lone pair repulsion lone pair versus bonding pair repulsion bonding pair versus bonding pair repulsion Molecular Geometry  Example There are two electron pairs around the central atom in a molecule with linear molecular geometry, 2 bonding electron pairs and 0 lone pairs. The ideal bond angle is 180 °. Geometry Type # of Electron Pairs Ideal Bond Angle Examples linear AB2 2 180 BeCl2 trigonal planar AB3 3 120 BF3 tetrahedral AB4 4 109.5 CH4 trigonal bipyramidal AB5 5 90, 120 PCl5 octohedral AB6 6 90 SF6 bent AB2E 3 120 (119) SO2 trigonal pyramidal AB3E 4 109.5 (107.5) NH3 bent AB2E2 4 109.5 (104.5) H2O seesaw AB4E 5 180,120 (173.1,101.6) SF4 T-shape AB3E2 5 90,180 (87.5,180) ClF3 linear AB2E3 5 180 XeF2 square pyramidal AB5E 6 90 (84.8) BrF5 square planar AB4E2 6 90 XeF4 Isomers in Molecular Geometry Molecules with the same chemical formula may have atoms arranged differently. The molecules are called isomers. Isomers may have very different properties from each other. There are different types of isomers: Constitutional or structural isomers have the same formulas, but the atoms are not connected to each other the same water.Stereoisomers have the same formulas, with the atoms bonded in the same order, but groups of atoms rotate around a bond differently to yield chirality or handedness. Stereoisomers polarize light differently from each other. In biochemistry, they tend to display different biological activity. Experimental Determination of Molecular Geometry You can use Lewis structures to predict molecular geometry, but its best to verify these predictions experimentally. Several analytical methods can be used to image molecules and learn about their vibrational and rotational absorbance. Examples include x-ray crystallography, neutron diffraction, infrared (IR) spectroscopy, Raman spectroscopy, electron diffraction, and microwave spectroscopy. The best determination of a structure is made at low temperature because increasing the temperature gives the molecules more energy, which can lead to conformation changes. The molecular geometry of a substance may be different depending on whether the sample is a solid, liquid, gas, or part of a solution. Molecular Geometry Key Takeaways Molecular geometry describes the three-dimensional arrangement of atoms in a molecule.Data that may be obtained from a molecules geometry includes the relative position of each atom, bond lengths, bond angles, and torsional angles.Predicting a molecules geometry makes it possible to predict its reactivity, color, phase of matter, polarity, biological activity, and magnetism.Molecular geometry may be predicted using VSEPR and Lewis structures and verified using spectroscopy and diffraction. References Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5.McMurry, John E. (1992), Organic Chemistry (3rd ed.), Belmont: Wadsworth, ISBN 0-534-16218-5.Miessler G.L. and Tarr D.A.  Inorganic Chemistry  (2nd ed., Prentice-Hall 1999), pp. 57-58.

George Schuyler, Black No More - 1591 Words

George Schuyler, Iconoclast in Black No More George S. Schuyler, according to Mark Gauvreau Judge, was born in Rhode Island in 1985 and died in 1977. Schuyler’s mother eventually remarried after the death of her first husband, and the family moved to Syracuse NY, where Schuyler was taught by her and his stepfather the protestant ethic of working for whatever he wanted to achieve (Rac(e)ing to the Right xv). Those teachings, along with learning from his mother to read at an early age, in all likelihood, were the catalyst to his becoming one of the most well-known â€Å"Aframerican† journalists in the United States and one of America’s first black conservatives, wrote Judge continued. Reconstruction never accomplished its objectives; African†¦show more content†¦Subsequently, as Schuyler’s views took a turn to the far right; he was named as one of the few black conservatives of his era (). He opposed the New Deal signed into law by FDR, supported Joseph McCarthy’s anti-Communist positio n and was against the Civil Rights Act of 1964 (). Additionally, Schuyler was mentored in the skill of satire and debate by H.L. Mencken, who became, not only Schuyler’s teacher but his friend (Judge). The Pittsburg Courier is where Schuyler spent forty years, losing his position after a scathing protest regarding Dr. Martin Luther King’s nomination for the Nobel Peace Prize (Kickler). No one was exempt from Schuyler’s scrutiny and criticism,† including the bigoted Ku Klux Klan, the charlatan, Marcus Garvey, the verbose W.E.B. Dubois or the over-praised authors associated with the Harlem Renaissance (Kicker). Jeffrey Ferguson wrote in The Sage of Sugar Hill that Schuyler looked at himself as a â€Å"useful irritant.† Schuyler, the iconoclast, functioned as a server of the truth (in his mind) to his readers whom he thought could not ferret it out for themselves. Using that same point of view Schuyler wrote Black No More, one the first works of Africa n American science fiction that explored what would happen if all the black people in the U. S. could become white (7). Science fiction or speculative fiction is defined by The Oxford Dictionary of Literary Terms as â€Å"a popular modern branch of prose fiction that explores the probableShow MoreRelatedBlack No More By George Schuyler797 Words   |  4 Pagescome. In the eighteen eighties Jim Crow Laws were passed that segregated Black individuals and often subjected them to humiliating conditions. These conditions exasperate and trouble all of the characters in the novel Black No More. In this novel by George Schuyler Blacks are degraded and oppressed because of the color of their skin. This oppression is caused by ignorant prejudices that individuals in the novel hold. Schuyler uses satire, elevated language, and imagery to further support the ideaRead MoreSummary Of The Iconoclast s Black No More 1718 Words   |  7 PagesIconoclast in Black No More A Black person learns very early that his color is a disadvantage in the world of white folk. This being an unalterable circumstance, one also learns very early to make the best of it. George S. Schuyler, Black, and Conservative George S. Schuyler, author of Black No More, was born in Rhode Island in 1885 and died in New York in 1977. Schuyler’s father died when he was three years old; his mother remarried, and the family moved to Syracuse, New York. There Schuyler was taughtRead MoreThe Harlem Renaissance By Langston Hughes1703 Words   |  7 Pages1920s and 1930s, to create unity amongst the black communities in the United States, the Caribbean and and Africa. Some common themes represented during the Harlem Renaissance were the influence of slavery, black identity, the effects of institutional racism, the dilemmas of performing and writing for elite white audiences, and how to convey the experience of modern black life in the urban North. To many, the Harlem Renaissance promoted a sense of black pride and allowed African Americans to distinguishRead MoreAnalysis Of The Movie Hamilton 1052 Words   |  5 Pageskeep up with even though it has a fast pace. The first act tells the story of revoluti on and how Hamilton meets his wife Eliza Schuyler. In this act, Hamilton is trying to make a name for himself by fighting in the war but instead becomes George Washington’s secretary. The second act is a bit more somber and has a slower pace. This act is also more dramatic and evokes more emotion. In this act Hamilton and the other founding fathers are trying to create the country from the ground up. Act two startsRead MoreColorism Within the Harlem Renaissance2864 Words   |  12 Pagesspecific I have found that it plays a more dominantly negative role in the lives of women and through literary and secondary source supports this paper will further express what colorism is and the affect it has on the women who face it at such a high racially tense time. I believe it is first important to have an understanding of the period of time known as the Harlem Renaissance. The Harlem Renaissance was a time period that begin in the 1920s [when] black intellectuals of Harlem had a ‘reawakening’Read MoreDuring The Exposition Of Richard Wright’S Native Son, Jan1067 Words   |  5 Pagesand initiates a cordial handshake with Bigger Thomas, a black boy. Bigger is highly suspicious of this gesture, so much so that he can barely bring himself to shake Jan’s hand. As a dark-skinned male 20-year old living in Chicago’s South Side during the 1930s, Bigger had good reason to be dubious of Jan’s intentions. It is not unlikely that he had not experienced this kind of interaction with a white person until this moment. To make matters more complicated, Mary Dalton, a white girl, is encouragingRead MoreThe Civil Rights Movement Of America1526 Words   |  7 Pageseverything else in between. It was steadily growing m ore and more unbearable for black people. The time for waiting was becoming shorter and the time for a change was at hand. Segregationist violence played a major factor in the push towards civil rights from blacks. On August 28, 1955, a fourteen-year-old black male, named Emmett Till was lynched for whistling at a white woman. â€Å"The crime was extremely brutal, and it was a reminder to the black community that whites would utilize all means, includingRead MoreJackie Robinson : African American Civil Rights Activist1181 Words   |  5 PagesGroups–Part 1, Hearings Before the Committee on Un-American Activities, House of Representatives, Eighty First Congress, First Session. 18 July. 1949. This is a transcript from 1949, when Jackie Robinson was summoned before the HUAC to discuss communism to Black America. He reminds the court that he is coming from a view of being a colored American, â€Å"with 30 years of experience†. Jackie follows to explain that democracy will only work for those who are willing to fight for it (addressed Negro Americans). Read MoreHistory5499 Words   |  22 Pagessees Harlem Renaissance used interchangeably with ‘‘New Negro Renaissance,’’ a term that includes all African Americans, regardless of their location, who participated in this cultural revolution. Followers of the New Negro dicta, which emphasized blacks’ inclusion in and empowerment by American society, were undeniably spread throughout the nation, and most major cities had pockets of the African-American elite that W. E. B. Du Bois dubbed the ‘‘Talented Tenth.’’ Nevertheless, New York City was,Read MoreThe Negro Artist And The Racial Mountain : The Manifesto For Artists Of The Harlem Renaissance1787 Words   |  8 PagesRenaissance was the â€Å"irresistible impulse of blacks to create boldly expressive art of a high quality as a primary response to their social conditions, as an affirmation of their dignity and humanity in the face of poverty and racism† (953). The Harlem Renaissance was known as the rebirth of music, drama, dance, literature, and art for African Americans from 1919-1940. During this time, Black Americans found themselves longing to gain acceptance from their own. Blacks needed to create art and literature to

General Environmental Pollution and the KyotoProtocol Free Essays

What is environmental pollution? It can be defined as the act of environmental contamination, usually caused by man-made wastes. The Environment and Opportunity Cost At first thought, these two concepts seem to be fairly unrelated. However, both of these concepts come down to one single principle – Scarcity. We will write a custom essay sample on General Environmental Pollution and the KyotoProtocol or any similar topic only for you Order Now As economists, we have seen that society tries to make the best arrangements between various resources in order to gain maximum benefit. Unfortunately, these arrangements which provide maximum benefit to an individual or firm can have detrimental side effects to other individuals and/or firms. Environmental problems would not arise if there was a superabundance of resources. There would be no worries about running out of supplies. Most waste products could be easily and harmlessly dispersed if there were boundless oceans and atmosphere. Many of our environmental problems occur simply because we have tended to treat world resources as if they were limitless. Scarcity forces upon us the necessity of making choices by comparing alternatives. We are all aware that if limited resources are fully employed, an increase in the output of one commodity or service can only be achieved by having less of another – more resources being used to clean-up the environment will mean fewer resources available for consumer goods. (Explain opportunity cost and trade off) (Explain shifting of PPC inwards in long run due to unhealthy workforce and hence less productivity of workforce – should we locate at A or at B? – Most developed nations would aim for B whilst most developing nations would really produce at A) (Explain minimum consumption limited – why points below/above are unachievable) Economic Causes of Environmental Pollution Environmental pollution is basically caused due to economic actions of a firm – i.e. production of a good or service. Environmental pollution is a form of a negative externality. Most economic actions of firms contribute towards some external cost. This is illustrated below. The cost of producing oil, to a firm is C. However, this is only the private cost of production of oil – i.e. the cost of manufacturing oil to the firm, which includes its fixed and variable costs. The firm pays C to produce an output of Q. However, it does not take into account the social cost of producing oil. The social cost is the private cost plus any external costs. In this case, the external cost is the vertical distance between the two supply curves, E1T. The oil factory emits harmful chemicals which damages the environment. This, in the long run, causes health problems for the local residents, as it contaminates the air, soil and water. These infected inhabitants will need to be treated at the NHS. This is ultimately funded by the government, who pays the cost of cleanup. In order to bare this cost on the firm, the government must try to equate MPC with MSC, as the product is currently being overproduced, from society’s point of view. In order to do this, it must set policies to shift the MPC curve leftwards to the MSC curve, by basically reducing supply. At this point, the cost to the firm will be C1 at an output level of Q1. At this reduced output level, a social optimum point will be reached. However, reducing production can lead to a firms cost increasing, as it moves leftwards on the AC curve. If such an increase in costs comes from a more vital product, say oil, it can cause cost-push inflation in the economy. We shall now take a real-life example of the French oil industry and a French oil company called TotalFinaElf. TFE has consistently been leading the list for the worst French polluters, followed by other French oil firms. The French government, a couple of years ago decided to implement more stringent policies in order to reduce pollution and environmental damage. The policies that were implemented have been discussed below. 1. The first policy implemented was a flat rate tax. The tax leads to an increase in the cost of production, a reduction in production and hence a reduction in pollution. The social optimum point of production is at OQ, where the firm pays tax equal to EQ. This is equal to its marginal profit in pollution and hence there is no profit on the last unit. However, the French government soon realised that such a policy was not very effective for a number of reasons. It placed the same amount of tax on producers regardless of their size and regardless how much they individually polluted the atmosphere. It was very difficult to place a monetary value on the extent of the damage and hence the tax rate. Oil is a necessity and has an inelastic demand. For this reason, the oil producers were able to pass on most of the tax cost onto the consumer and hence it had no effect on reducing pollution caused by these firms. 2. Another policy that was thought of, but not implemented was a form of regulation. Under this policy the French government would allow production of oil of OQ barrels. Beyond this limit, the French government decided to ban production of oil. However, this policy was not put into effect because of the fact that demand for oil is inelastic. Reducing supply, would lead to an increase in price and hence cost-push inflation. (Draw diag.) The French government has still not decided on an appropriate policy to implement. The French government is trying to implement a policy which combines property rights and environmental taxes. They have realised that it is very difficult to extend property rights and identify the polluter. The Kyoto Protocol The policies implemented by various nations, to limit greenhouse gas emissions have had a fairly adverse effect on their economies and industries. The Kyoto Protocol was set up to alleviate these adverse effects and to continue pursuing the goal of reducing pollution and environmental degradation. The purpose of the mechanisms described in the protocol, entails channeling investments in energy efficient and energy conservation to countries and projects where the cost per unit of emissions reduction is lowest. This concept would entail a large-scale resource transfer from relatively energy-efficient, high cost countries to energy-inefficient, low cost countries. The pact requires industrialised countries to reduce their greenhouse gas emissions by 8% of the 1990 levels between 2008 and 2012 The establishment of emissions reduction targets was a very complicated issue in the early phase of the international negotiations. Many countries could point to special circumstances that justified a more lax treatment of them compared to other countries. This argument was accepted to a limited extent. Notably, Russia and the Ukraine were given a zero target as opposed to the western industrialized countries that would have to reduce their emissions by 2010. The Kyoto Protocol uses a system of pollution permits which can be traded on an international market. The USA is opposed to this treaty, because it claims that it will have a devastating effect on its economy. It claims that it will lead to serious job losses, inflation and a fall in GDP. How – We have seen that pollution occurs because of overproduction and over consumption. Reducing production will lead to more factors of production becoming unemployed, and also a fall in GDP. This has brought various criticisms, especially from the UK. All nations claim that the USA, by a large margin, is the world’s largest polluter and hence should sign the treaty for the well-being of future generations. â€Å"The US contains 4% of the world’s population but produces about 25% of all carbon dioxide emissions. By comparison, Britain emits 3% – about the same as India which has 15 times as many people† Source: BBC President Bush â€Å"Under the Protocol, the U.S. is supposed to cut its greenhouse gas emissions by seven percent. With four percent of the world’s population, the country accounts for about 25 percent of the Earth’s greenhouse gas emissions† European Environment Commissioner Margot Wallstrà ¯Ã‚ ¿Ã‚ ½m says ‘But this ignorant, short sighted and selfish politician, long since firmly jammed into the pockets of the oil lobby, clearly couldn’t care less. The talks in Bonn in July must now concentrate on world action independent of the U.S.’ â€Å" How to cite General Environmental Pollution and the KyotoProtocol, Papers