The Periodic Properties of the Elements

The periodic table arranges the elements  by periodic properties, which are recurring trends in physical and chemical characteristics. These trends can be predicted merely by examing the periodic table and can be explained and understood by analyzing the electron configurations of the elements. Elements tend to gain or lose valence electrons to achieve stable octet formation. Stable octets are seen in the inert gases, or noble gases, of Group VIII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electrons become closer to the nucleus and more tightly bound to it. Second, moving down a column in the periodic table, the outermost electrons become less tightly bound to the nucleus. This happens because the number of filled principal energy levels (whi ch shield the outermost electrons from attraction to the nucleus) increases downward within each group. These trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity, and electronegativity. Atomic Radius The atomic radius of an element is half of the distance between the centers of two atoms of that element that are just touching each other. Generally, the atomic radius decreases across a period from left to right and increases down a given group. The atoms with the largest atomic radii are located in Group I and at the bottom of groups. Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons. Since the number of protons is also increasing, the effective nuclear charge increases across a period. This causes the atomic radius to decrease. Moving down a group in the periodic table, the number of electrons and filled electron shells increases, but the number of valence electrons remains the same. The outermost electrons in a group are exposed to the same effective nuclear charge, but electrons are found farther from the nucleus as the number of filled energy shells increases. Therefore, the atomic radii increase. Ionization Energy The ionization energy, or ionization potential, is the energy required to remove an electron from a gaseous atom or ion completely. The closer and more tightly bound an electron is to the nucleus, the more difficult it will be to remove, and the higher its ionization energy will be. The first ionization energy is the energy required to remove one electron from the parent atom. The second ionization energy is the energy required to remove a second valence electron from the univalent ion to form the divalent ion, and so on. Successive ionization energies increase. The second ionization energy is always greater than the first ionization energy. Ionization energies increase moving from left to right across a period (decreasing atomic radius). Ionization energy decreases moving down a group (increasing atomic radius). Group  I elements have low ionization energies because the loss of an electron forms a stable octet. Electron Affinity Electron affinity reflects the ability of an atom to accept an electron. It is the energy change that occurs when an electron is added to a gaseous atom. Atoms with stronger effective nuclear charge have greater electron affinity. Some generalizations can be made about the electron affinities of certain groups in the periodic table. The Group IIA elements, the alkaline earths, have low electron affinity values. These elements are relatively stable because they have filled s subshells. Group VIIA elements, the halogens, have high electron affinities because the addition of an electron to an atom results in a completely filled shell. Group VIII elements, noble gases, have electron affinities near zero since each atom possesses a stable octet and will not accept an electron readily. Elements of other groups have low electron affinities. In a period, the halogen will have the highest electron affinity, while the noble gas will have the lowest electron affinity. Electron affinity decreases moving down a group because a new electron would be further from the nucleus of a large atom. Electronegativity Electronegativity is a measure of the attraction of an atom for the electrons in a chemical bond. The higher the electronegativity of an atom, the greater its attraction for bonding electrons. Electronegativity is related to ionization energy. Electrons with low ionization energies have low electronegativities because their nuclei do not exert a strong attractive force on electrons. Elements with high ionization energies have high electronegativities due to the strong pull exerted on electrons by the nucleus. In a group, the electronegativity decreases as the atomic number increases, as a result of the increased distance between the valence electron and nucleus (greater atomic radius). An example of an electropositive (i.e., low electronegativity) element is cesium; an example of a highly electronegative element is fluorine. Summary of Periodic Table Properties of Elements Moving Left → Right Atomic Radius DecreasesIonization Energy IncreasesElectron Affinity Generally Increases (except Noble Gas Electron Affinity Near Zero)Electronegativity Increases Moving Top → Bottom Atomic Radius IncreasesIonization Energy DecreasesElectron Affinity Generally Decreases Moving Down a GroupElectronegativity Decreases

Thoughtful Questions and Answers on the Declaration of...

1. Jefferson wrote, †¦That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government†¦ Clearly describe three examples from any period of American History when Americans attempted to follow these words. One example of a time that Americans attempted to alter or change the U.S. Government was during the civil war. At this time, Southern (Confederate) states tried to withdraw from the union. Another example is how since the 1990s, Texas has had certain pleas to leave the nation and become the Republic of Texas. An even more recent example is members and candidates of the Tea Party. Ironically named after the Boston Tea Party of 1773, these†¦show more content†¦You are NOT limited to the groups listed as examples. Do you agree or disagree with their viewpoints? Explain. You need to describe the groups and explain the abuses and usurpations that they object to fully. One group that I can think of off the top of head that definitely opposes American government is the terrorist group Al-Qaeda. Not only do they oppose American government but they really oppose all western countries’ governments. They are a radical group that believes that the entirety of all governments will collapse when the U.S. falls and they consequently believe that these governments need to be replaced and taken over by Al-Qaeda leaders of the Sunni Islamic beliefs. I believe that this is entirely severe and irrational. I do not think that all of their problems with the U.S. are accurate however America certainly is not perfect either. On a slightly less severe note, another group in today’s society that opposes U.S. government is militia men. They believe that government should be localized to individual counties and that these counties should be independent. They do not believe that they should be burdened to pay federal taxes or that they should have to register vehicles and any government duties that stray from local government. I do not believe that this is efficient for the current world that we live in. We can learn from history, in the times of the middle ages when Europeans lived in independent small kingdoms or tribes to moreShow MoreRelatedEssay on Korea6392 Words   |  26 Pagesimmemorial Koreans believed in the existence of one Lord of heaven and earth as well as numerous lesser spirits. From earliest times Koreans have experienced direct contact with supernatural powers. Furthermore, shamanism emphasized Koreas unique role in history. Traditionally, Koreans dressed in white, because this symbolized their faith that they were children of the divine light. For centuries the shamans taught that Koreans had been chosen for a special purpose in Gods plan for mankind. 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Business Culture in Turkey Free Essays

Business Culture Overview A brief overview of Etiquette/Relationships, Business Negotiations, and Communication when dealing with business in Turkey. Etiquette and Relationships Business etiquette in Turkey revolves around personal relationships. Appointments are necessary and should be made in advance. We will write a custom essay sample on Business Culture in Turkey or any similar topic only for you Order Now Avoid making these appointments during Ramadan and the months of July and August. Be punctual, although be prepared to be kept waiting for appointments or meetings. Small talk is welcomed during business meetings, do not open up with the business matter at hand immediately. Have all documents in English and Turkish, as well to include charts, graphs, and visual aids. When dressing for business in Turkey, it should be conservative. Exchanging of business cards is a sign of trust from most businessmen. It is important to shake hands when entering, however not so when departing. Business Negotiation Always come to Turkey knowing two things. Success is defined by your ability to establish to build effective personal relationships. Business is personal. Many businesses are still family run although it is changing with MNC’s growing fast. The first meeting is purely social, then from there it will be about business. Do not include any surprises or mystery to your proposal. They are more inclined to visual objects, so include charts, graphs, statistics in presentation. Decision making tends to be slow, it has to pass from less senior members all the way up the hierarchy. Turkish businessmen will start at extremes to engage responses. Know your target figure and work to compromise to a number in the middle. Do not use any pressure tactics or abrupt deadlines because they will just reverse this tactic right back at you and it may drive them away from the deal. Communication Turkish people prefer to conduct business with people they are very trustworthy of. Courtesy is crucial in all business settings. Stand close while conversing, do not back away as it considered rude. Do not be impatient, many initial questions will not be about the topic at hand, but rather about family, children, soccer and more. Turks are proud to answer questions about their history, culture, but avoid political history. It is vital to maintain eye contact while talking, it is a sign of sincerity. Make sure any gifts are appropriate if given. It is not customary for them to exchange gifts in a business setting however. How to cite Business Culture in Turkey, Papers

Cogito Ergo Sum free essay sample

Posted on the door to my room is the phrase, â€Å"I think, therefore I am†. Descartes explains that human’s exist because they can intuitively understand the truth that they exist. Broadened, the phrase represents other facets of philosophical thought. Thought produces great works of art, literature, music, mathematics, and science. It is thought that moves the human race forward. Still, perhaps thought is not enough. Emotions are a large part of the process of learning. Perhaps the phrase should instead be, â€Å"I feel, therefore I am†. In any case, we do not usually follow a logical thought process to know that we exist; Instead we have an intuitive understanding of our existence. In order to truly learn something, emotional attachment and reaction must be involved. For this reason, one must be completely immersed in an atmosphere that fosters creative growth. Skidmore’s motto states, â€Å"Creative Thought Matters†, a mantra that argues creati vity is important. We will write a custom essay sample on Cogito Ergo Sum or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page To be creative, one has to genuinely feel and understand whatever one’s interests are. The moment I stepped onto the Skidmore campus I felt an atmosphere permeated with knowledge and knew I wanted to be a student there. To succeed, I need an atmosphere that fosters creativity instead of trampling on it like some more traditional institutions. As a musician I was first drawn to the Zankel Music Center and the Helen Filene Ladd Concert Hall. I was especially struck by the fact that the practice rooms had windows. To be able to look out onto the campus while practicing or composing was especially enticing to me because I like to feel as though I can be inspired by the nature around me. I was also interested in the First Year Experience. Each Seminar seemed incredibly interesting and I wished I could take all of them! The synthesis of an intellectual atmosphere and numerous opportunities offers me what I need to succeed as a â€Å"thinker† and a â€Å"feeler† and wi ll prepare me to go out into my world a capable and mature person.