Periodic Table Definition in Chemistry

The periodic table is a tabular arrangement of the chemical elements by increasing atomic number which displays the elements so that one may see trends in their properties. The Russian scientist Dmitri Mendeleev is most often credited with inventing the periodic table (1869) from which the modern table is derived. Although Mendeleevs table ordered the elements according to increasing atomic weight rather than atomic number, his table illustrated recurring trends or periodicity in the element properties. Also Known As: Periodic Chart, Periodic Table of the Elements, Periodic Table of the Chemical Elements Key Takeaways: Periodic Table Definition The periodic table is a tabular arrangement of chemical elements that is arranged by increasing atomic number and groups elements according to recurring properties.The seven rows of the periodic table are called periods. The rows are arranged so that metals are on the left side of the table and nonmetals are on the right side.The columns are called groups. Group contain elements with similar properties. Organization The structure of the periodic table makes it possible to see relationships between elements at a glance and predict properties of unfamiliar, newly discovered, or undiscovered elements. Periods There are seven rows of the periodic table, which are called periods. Element atomic number increases moving from left to right across a period. Elements toward the left side of a period are metals, while those on the right side are nonmetals. Groups The columns of elements are called groups or families. Groups are numbered from 1 (the alkali metals) to 18 (the noble gases). Elements within a group display a pattern with respect atomic radius, electronegativity, and ionization energy. Atomic radius increases moving down a group, as successive elements gain an electron energy level. Electronegativity decreases moving down a group because adding an electron shell pushes the valence electrons further from the nucleus. Moving down a group, elements have successively lower ionization energies because it becomes easier to remove an electron from the outermost shell. Blocks Blocks are sections of the periodic table that indicate the outer electron subshell of the atom. The s-block includes the first two groups (the alkali metals and the alkaline earths), hydrogen, and helium. The p-block includes groups 13 to 18. The d-block includes groups 3 to 12, which are transition metals. The f-block consists of the two periods below the main body of the periodic table (the lanthanides and actinides). Metals, Metalloids, Nonmetals The three broad categories of elements are metals, metalloids or semimetals, and nonmetals. Metallic character is highest at the bottom lefthand corner of the periodic table, while the most nonmetallic elements are in the upper righthand corner. The majority of chemical elements are metals. Metals tend to be shiny (metallic luster), hard, conductive, and capable of forming alloys. Nonmetals tend to be soft, colored, insulators, and capable of forming compounds with metals. Metalloids display properties intermediate between those of metals and nonmetals. Toward the right side of the periodic table, the metals transition into nonmetals. There is a rough staircase pattern—starting at boron and going through silicon, germanium, arsenic, antimony, tellurium, and polonium—that identified the metalloids. However, chemists increasingly categorize other elements as metalloids, including carbon, phosphorus, gallium, and others. History Dmitri Mendeleev and Julius Lothar Meyer independently published periodic tables in 1869 and 1870, respectively. However, Meyer had already published an earlier version in 1864. Both Mendeleev and Meyer organized elements by increasing atomic weight and organized elements according to repeating characteristics. Several other earlier tables were produced. Antoine Lavoisier organized elements into metals, nonmetals, and gases in 1789. In 1862, Alexandre-Emile BÃ ©guyer de Chancourtois published a periodic table called the telluric helix or screw. This table was probably the first to organize elements by periodic properties. Sources Chang, R. (2002). Chemistry (7th ed.). New York: McGraw-Hill Higher Education. ISBN 978-0-19-284100-1.Emsley, J. (2011). Natures Building Blocks: An A-Z Guide to the Elements. New York, NY: Oxford University Press. ISBN 978-0-19-960563-7.Gray, T. (2009). The Elements: A Visual Exploration of Every Known Atom in the Universe. New York: Black Dog Leventhal Publishers. ISBN 978-1-57912-814-2.Greenwood, N. N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 978-0-08-022057-4.Meija, Juris; et al. (2016). Atomic weights of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305

The United States And The Civil War - 1622 Words

All Men are created equal, that they are endowed by their Creator with certain unalienable Rights that among there are Life, Liberty, and the Pursuit of Happiness (Declaration of Independence). According to the U.S. Constitution the purpose for which the United States was created was to establish a perfect union within the citizens of the U.S. through justice, safety, welfare and liberty. In my opinion, although the U.S. Constitution states this, I do not believe this perfect union is in favor for everyone in this country because of the unjust events that have taken places within this country such as slavery. I believe the U.S. Constitution purpose only applies to those who are in higher power. The Civil War started because of unbending†¦show more content†¦The United States was created for the states by the states and its purpose was to establish a perfect union within the colonies through justice, and liberty. Moreover they wanted to keep the ideas of Locke since the colo nies believed that England has become a corrupt nation. So, it was their job to protect the ideas gained during the Glorious Revolution and Americans saw their nation as a rising empire, destined to populate and control the entire globe (Foner). A century later, the differences between the free and slave states over the power of the national government to prohibit slavery in the new territories obtained from the Mexican War had created discrepancies within the Union. The result of these differences led to the Civil War, which was an important event in America s Enlightenment. Furthermore, we need to remember that the American Revolution (1776-1783) created the United States; the Declaration of Independence is the document that the founders of the nation wrote to express what they wanted for the new nation. On the other hand, the Civil War (1861-1865) determined what kind of nation it would be because the war tried to resolve points omitted by the Revolution. One of these points was that whether the United States was to keep having slavery as an economic system. Moreover, if the Union, which

The Classical Style Of The Ancient Greece And The United...

Neo- Classicism in France and the United States The classical style of the ancient Athens, derived from Ancient Greece and Ancient Rome in the 15th century, has had a universal impact on many cultures during previous time periods. The classical period reflected traditional forms focused on symmetry and elegance; it flourished during the time of the Renaissance through artist such as Michelangelo, Raphael, and Leonardo De Vinci. The artists’ main goal was to attain the absolute beauty in their art by showing emotion through detail, almost through perfection. Some examples of well-known classical arts during the Renaissance were ‘Belvedere Torso’ and the ‘Medici Venus’. In the 17th century the classical style was revived, now called the neo-classical style. It was born in Rome but its popularity flourished all over Europe. The neo-classical movement clashed with the age of Enlightment and continued through the 19th century. The neo-classical principles were based around the same characteristics as t he classical arts such as: balance, proportion, order, simplicity, clarity, and reason. It was strongest in architect, sculpture, and decorative arts. The neo- classical style continued to spread throughout the world and became sought after in the 17th and 18th century in countries such as France and The United States, and it influenced some of the greatest government buildings in America. Neoclassicism can be seen as a political movement as well as an artistic and cultural one.Show MoreRelated Classical Architecture Essay595 Words   |  3 PagesClassical Architecture The West has always put a great emphasis on how beholden it is to many cultural and political institutions derived from Classical Antiquity. This has been most consistent in aesthetic conceptions of art and architecture. 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Develop A User Centered Design of Insurance

Question: Discuss about the Develop A User Centered Design of Insurance . Answer: Aim The aim of the project is to develop a user-centered design for solving the problem of under-insurance of daily use appliances of common people. Most of the users ignore that fact these appliances can be insured and use them without proper insurance. Hence, if the appliances somehow get damaged or destroyed, these users cannot get back the fraction of the price they paid for the appliances. On the other hand, some insurance companies cheat the users and pay less money in the event of destruction of an usable appliance. In order to solve these problems, this project is planned to develop a user-centered design that will address the issues discussed. Context of Use Two different user groups of this software are the consumers and the insurance companies. The contexts of use of this software are shown in the following table. Consumers Insurance Companies Goals/Role in System The consumers should use this software in order to ensure that their daily use appliances are all properly insured and the insurance companies are not cheating them by any means. The companies should use this software in order to maintain a clean relationship with the customers as well as avoid mishandling of the customers insurance money. Tasks Using this software, the consumers should update their insurance statuses as well as requirements regarding investment or return of insurance money. Moreover, they can keep themselves updated with the changing insurance policies and fluctuating values of money. The companies can keep an updated records of the customers including their investment or withdrawal histories. This will also enable them to calculate the available balance for each customer and classify customer requests based on priorities. Physical Environment The customers can use the software anytime from their home or outside based on the device used. If a dedicated mobile app is developed for supporting the software, the user can access it anytime anywhere. The company should only have access to the software inside office premises. The software should contain sufficient amount of personal information of the clients and as a result, the software should not be used outside in order to prevent leak of secure information. Technology and Artifacts The main target technology for consumers is smartphone. It has been seen that many of the customers do not have access to computers but a vast majority has access to smartphones. Hence, if the software is developed for smartphone, more consumers can be earned. The targeted technology for the companies is computer. Using the computer, the company can efficiently use the software and store necessary data in virtual storage interfaces. Social Environment Interaction feature may be added so that consumers can interact with each other using the software. There can be chat option inside the software where interaction is possible. The company will handle a lot of confidential information and hence, no chat options are required. Necessary interactions can be conducted face to face inside office premises. Problems The main problem is that most of the consumers are accustomed to the use of such a software and hence, the design should be made as simple and user-centric as possible. The main problem is that most of the insurance companies have sufficient tech support. Hence, they need to update their technical setup and ensure sufficient maintenance in order to support the new software. Moreover, they also require data security in order to protect confidential and personal information of the customers. Application of UCD Principles There are certain UCD principles that are to be followed while developing a user-centered design for a particular purpose. In the provided case study, a user-interface design is to be created for solving the problem of under-insurance of home appliances of a user including bed, computer, books, cooking utensils, electrical appliances and others. However, the implementation is not possible without complying with the basic UCD principles. The compliance details with the UCD principles are as follows. Principle 1 This principle states that the design is based on the explicit understanding of users, tasks and environment. As the name of the assignment suggests, all the designs must be centered around the user. In other words, the design should be made purely based on the basic understanding and knowledge of the user, tasks and the use environment. In this case, the users as well as the insurance companies must fully understand the working of the design and be able to apply their knowledge in handling the design in the right manner. Principle 2 This principle states that users are involved throughout the design and development. Users must be involved throughout the course of the design and development. However, since active participation may not be possible, passive participation is suggested. This can be done by releasing demo versions that can be used and tested by the users. Further modifications of the design will then be possible following the user feedbacks regarding bugs or improvements. Principle 3 This principle states that the design is driven and refined by user-centered evaluation. The design will definitely be driven and refined by user-centered evaluation. As mentioned in the previous principle, demo versions of the design should be release for the users to test. After testing, they can provide feedbacks regarding existing bugs or issues. Following these feedbacks, suitable changes can be made to the design. Principle 4 According to this principle, the overall design process is iterative. Development of user-centered design is always iterative in nature. During the development life cycle, the development is done through a number of iterative processes. This helps to remove bugs and identify errors during the development process. If in one iteration, an error is detected, changes are made and the iteration is repeated. The development is complete when the final iteration does not show any more errors. Principle 5 This principle states that the design will address the whole user experience. Since the design is user-centric, it must be able to address the whole user experience. Users will be only interested in the design if it enhances user experience and provides great value during its operation and handling. In the opposite case, the users will not accept the design and the project will be a failure. Principle 6 According to this principle, the design team include multidisciplinary skills and perspectives. Any team requires multidisciplinary skills and perspectives in order to provide a number of approaches to the same project. Some perspective may be right but is not feasible for the project. A variety of skills and perspectives will solve this issue and enhance the quality of the project outcome.