Atomic Structure

The Rutherford Model of the Atom 1. In 1911 Rutherford proposed the nuclear model of atomic structure. He suggested that an atom consists of a central nucleus (where most of the mass of the atom is concentrated) having a positive charge, surrounded by moving electrons carrying negative charge. Geiger and Marsden carried out an experiment to verify his proposal. The Geiger/Marsden a Particle Scattering Experiment 1. The apparatus is illustrated in the diagram below. | 2. The apparatus was in an evacuated container. The detector was a ZnS screen observed through a low power microscope. Each time an alpha particle hit the screen, a small flash of light was produced. 3. The detector was mounted on a support such that it could be rotated to measure the angular deflection of the alpha particles as they passed through a very thin sheet of gold. They measured the numbers of particles deflected through various angles. 4. It was found that most of ? particles pass through the gold undeflected; only a relatively small number are deflected (scattered). 5. Their results were considered to confirm Rutherford’s model and allowed them to estimate the size of the nucleus (greater than 10-14m) and the size of the atom (greater than10-10m), thus producing the slightly surprising conclusion the most of the space occupied by an atom is empty space! Closest Approach of an Alpha Particle to a Nucleus 1. For a given speed of alpha particle, the closest approach to a nucleus, rmin, will occur when the initial direction of motion of the particle is along the line joining the centers of particle and nucleus. 2. In this case, at the point of closest approach, the speed of the particle is zero. 3. As the particle approaches the nucleus, kinetic energy is being converted to electrical potential energy. K. E. lost = E. P. E. gained| 4. Electrical potential at a distance r from a point charge Q is given by | 5. For a nucleus of atomic number Z, the charge is Ze, where e is the magnitude of the charge on one proton (the same as the magnitude of the charge on an electron). 6. The magnitude of the charge on an alpha particle is 2e 7. Therefore, the energy, w, possessed by an alpha particle placed at distance, rmin, from a charge Ze is given by | 8. So, we have | which gives | Millikan’s Experiment to Measure the Charge on one Electron 1. The diagram below is a very simplified representation of Millikan’s apparatus. | 2. Small drops of oil were allowed to fall into a region between two metal plates, (the top plate had a hole in it). 3. Some of the drops became charged by friction. Further ionization was caused by a beam of x rays. 4. Millikan measured the terminal speed of a drop as it fell through the air, with V = 0. From this he could calculate the radius of the drop (and hence it’s mass). He then applied a voltage, V, to the plates and measured the new terminal speed of the same drop. 5. The change in the terminal speed of the drop was used to calculate the magnitude of the charge on the drop. 6. When many measurements had been done, all the charges were found to be integral multiples of a basic unit of charge, assumed to be the charge on one electron. 7. The value, e, is approximately -1. 6? 10-19 C. 8. A simplified version of Millikan’s experiment can be done by finding the voltage needed to just hold an oil drop stationary between the two plates. 9. Consider a drop having a charge q and mass m. | 10. If the drop is stationary, then the two forces acting on it have equal magnitudes. where E is the field strength. 11. Now, , where d is the distance between the plates, Therefore The Electron Volt (eV) 1. The electron Volt is a unit of work (or energy) much smaller than the Joule. 2. If 1electron moves through a potential difference of 1V then 1eV of work is done. Relation between the Joule and the electron Volt 1. Potential difference is work done per unit charge so, . 1 J is the work done when 1C moves through a p. d. of 1V. 2. The charge on one electron is -1. 6? 10-19 C. 3. Therefore 1eV is the work done when 1 ·6? 10-19C moves through a p. d. of 1V. This means that . 4. To convert energy in J to energy in eV, Experiment to measure the Charge to Mass Ratio of Electrons 1. The method proposed here is similar to that used by J. J. Thomson in 1897. Electrons in an evacuated tube (a â€Å"cathode ray tube†) are sent towards a region of space where there are electric and magnetic fields at 90 ° to each other. If the field strengths have a particular ratio then charged particles can pass through them undeflected. | | | 2. In the following analysis | | | V = voltage accelerating the electrons and producing the electric field between the plates| | v = speed of the electrons| | m = mass of one electron and e = charge on one electron| | E = electric field strength (E = where d = distance between plates)| | B = magnetic flux density| 3. If the electrons pass undeflected (magnitude of electric force equal to magnitude of magnetic force), then it can easily be shown that | 4. To find the speed of the electrons, remember that during acceleration the electrons are losing electric P. E. and gaining K. E. | | E. P. E. lost = K. E. gained| eV = 5. Therefore, | | | 6. Combining equations 1 and 2 to eliminate v gives, | | | | 7. Thus, using his experimental apparatus, Thomson was able to determine the charge-to-mass ratio of the electron. Today, the accepted value of is C kg-1. Atomic Structure The Rutherford Model of the Atom 1. In 1911 Rutherford proposed the nuclear model of atomic structure. He suggested that an atom consists of a central nucleus (where most of the mass of the atom is concentrated) having a positive charge, surrounded by moving electrons carrying negative charge. Geiger and Marsden carried out an experiment to verify his proposal. The Geiger/Marsden a Particle Scattering Experiment 1. The apparatus is illustrated in the diagram below. | 2. The apparatus was in an evacuated container. The detector was a ZnS screen observed through a low power microscope. Each time an alpha particle hit the screen, a small flash of light was produced. 3. The detector was mounted on a support such that it could be rotated to measure the angular deflection of the alpha particles as they passed through a very thin sheet of gold. They measured the numbers of particles deflected through various angles. 4. It was found that most of ? particles pass through the gold undeflected; only a relatively small number are deflected (scattered). 5. Their results were considered to confirm Rutherford’s model and allowed them to estimate the size of the nucleus (greater than 10-14m) and the size of the atom (greater than10-10m), thus producing the slightly surprising conclusion the most of the space occupied by an atom is empty space! Closest Approach of an Alpha Particle to a Nucleus 1. For a given speed of alpha particle, the closest approach to a nucleus, rmin, will occur when the initial direction of motion of the particle is along the line joining the centers of particle and nucleus. 2. In this case, at the point of closest approach, the speed of the particle is zero. 3. As the particle approaches the nucleus, kinetic energy is being converted to electrical potential energy. K. E. lost = E. P. E. gained| 4. Electrical potential at a distance r from a point charge Q is given by | 5. For a nucleus of atomic number Z, the charge is Ze, where e is the magnitude of the charge on one proton (the same as the magnitude of the charge on an electron). 6. The magnitude of the charge on an alpha particle is 2e 7. Therefore, the energy, w, possessed by an alpha particle placed at distance, rmin, from a charge Ze is given by | 8. So, we have | which gives | Millikan’s Experiment to Measure the Charge on one Electron 1. The diagram below is a very simplified representation of Millikan’s apparatus. | 2. Small drops of oil were allowed to fall into a region between two metal plates, (the top plate had a hole in it). 3. Some of the drops became charged by friction. Further ionization was caused by a beam of x rays. 4. Millikan measured the terminal speed of a drop as it fell through the air, with V = 0. From this he could calculate the radius of the drop (and hence it’s mass). He then applied a voltage, V, to the plates and measured the new terminal speed of the same drop. 5. The change in the terminal speed of the drop was used to calculate the magnitude of the charge on the drop. 6. When many measurements had been done, all the charges were found to be integral multiples of a basic unit of charge, assumed to be the charge on one electron. 7. The value, e, is approximately -1. 6? 10-19 C. 8. A simplified version of Millikan’s experiment can be done by finding the voltage needed to just hold an oil drop stationary between the two plates. 9. Consider a drop having a charge q and mass m. | 10. If the drop is stationary, then the two forces acting on it have equal magnitudes. where E is the field strength. 11. Now, , where d is the distance between the plates, Therefore The Electron Volt (eV) 1. The electron Volt is a unit of work (or energy) much smaller than the Joule. 2. If 1electron moves through a potential difference of 1V then 1eV of work is done. Relation between the Joule and the electron Volt 1. Potential difference is work done per unit charge so, . 1 J is the work done when 1C moves through a p. d. of 1V. 2. The charge on one electron is -1. 6? 10-19 C. 3. Therefore 1eV is the work done when 1 ·6? 10-19C moves through a p. d. of 1V. This means that . 4. To convert energy in J to energy in eV, Experiment to measure the Charge to Mass Ratio of Electrons 1. The method proposed here is similar to that used by J. J. Thomson in 1897. Electrons in an evacuated tube (a â€Å"cathode ray tube†) are sent towards a region of space where there are electric and magnetic fields at 90 ° to each other. If the field strengths have a particular ratio then charged particles can pass through them undeflected. | | | 2. In the following analysis | | | V = voltage accelerating the electrons and producing the electric field between the plates| | v = speed of the electrons| | m = mass of one electron and e = charge on one electron| | E = electric field strength (E = where d = distance between plates)| | B = magnetic flux density| 3. If the electrons pass undeflected (magnitude of electric force equal to magnitude of magnetic force), then it can easily be shown that | 4. To find the speed of the electrons, remember that during acceleration the electrons are losing electric P. E. and gaining K. E. | | E. P. E. lost = K. E. gained| eV = 5. Therefore, | | | 6. Combining equations 1 and 2 to eliminate v gives, | | | | 7. Thus, using his experimental apparatus, Thomson was able to determine the charge-to-mass ratio of the electron. Today, the accepted value of is C kg-1.

Management Skills Case Study Example | Topics and Well Written Essays - 500 words

Management Skills - Case Study Example I am a company man and have been inspired by our company's long history of success and our stellar reputation. However, this has never proven very effective in my dealing with Eddie. I have made a plan to appeal to Eddie's confidence, materialism, and sense of independence. Eddie is motivated by material gain, but it is currently tied to his individual performance. Using task theory, I plan to tie Eddie's pay to organizational level criteria, such as company revenue and business growth (Miner, 1993, p. 27). This will be accompanied by the new title of 'Revenue Coordinator'. This will instill a new sense of importance in Eddie, and he will begin to use his team to accomplish company goals, rather than simply meeting departmental quotas. Eddie's team has complained that he is micro-managing them and they are resentful. I point out to Eddie that he is a top performer and that the other team members are somewhat jealous and intimidated by him, and they dislike him telling them 'how to do their job'. I suggest to Eddie that he create a system of recognition to honor the team member that most excels on a weekly and monthly basis. The reward will be in the form of a prize or merchandise that the winner can select.

Aquinas' Endless Time Theory integrated with Men in Black Essay

Aquinas' Endless Time Theory integrated with Men in Black - Essay Example This is a dimension with several scales that assists the whole universe to fit into the marble of an alien, within a larger universe. This is still within a similar alien locker and dimension. The alien locker is thus, a container for the entire dimension and its door enters a closed dimension within one of its own smaller scales. Basically, the alien locker is dimensionally transcendental similarly to Doctor whose tardis, with an interior which exists in several different dimensions compared to the exterior. Therefore, it has the ability to have different sizes on the outside and the inside (Stump and Padgett 163). According to Aquinas, the pattern of the sky has occasionally been a source on contradiction and wonder. In response to mysteries that human being experience in the course of their lives, answers to these questions are being sought. The seemingly unsubstantial clouds gliding the way through vision of human beings are heavy-laden with answers and secrets of the ending of t he earth. These usually come in form of visions to human beings and are only delivered to them when they are prepared to receive the message. The integration comes in that, in Men in Black, the most obvious and significant features of the universe is not valued, but taken for granted. Sometimes these features are entirely ignored as people go about their daily business in the film. This makes 'truth' a major theme in Men in Black as people are always accustomed to early things as it is the place where they live. According to Aquinas, these obvious features heavily contain truths which are similar to any occult wisdom which requires keenness for a better understanding. Over the recent past, some scholars took a positive initiative of solving the old day’s scientific problems and began revolution. They discovered the processes that inform nature's design in daily lives of human’s beings such as the shape of a leaf, and the curling of the smoke from a chimney among others (Jackele?n 69). According to scientists, the process of world within a world as shown in Men in Black will likely go on forever. This is because, over the last 14 million years, there has been expansion and cooling of the universe which sometimes forms the galaxies, and this trend is to continue forever. They argue that space, matter, and time are things which came into existence millions of years ago and will most likely continue to exist. Different scientists and philosophers have always described these intervening events in their own name which later became their theories of endless time. They describe these events which they argue that are responsible for the structure of the globe seen today and that it occurred several years ago. What is interesting is that, over the recent past, people are being motivated to explain the increasing elements which they continue to observe as the universe continues to evolve. According to Aquinas, the emergence of these theories in just a new w ay of explaining the recent happening and perceiving reality when it comes to time and space. The apparent absurdity about the endless space will have no ramifications for Aquinas' argument that the endless time is absurd. This is because, it is now evident that the predetermined and simple laws results to vastly complex effects on time and space. This complexity of nature is resulting from several principles and holism factors which are interacting (Stump and Padgett 163). In Men in Black, the basic shapes of nature and

The Future of Drinking Water Essay Example | Topics and Well Written Essays - 1500 words - 1

The Future of Drinking Water - Essay Example The primary sector comprises the primary production of raw materials or food, while the secondary sector concerns on the processing or refining of the produced goods or raw materials. As to the distribution of the finished products, the whole concern of it lies on the tertiary sector. However, all of these sectors require the availability or abundance of quality drinking water for them to function smoothly as possible. For instance, a quality and abundant drinking water source is necessary to ensure the sustainability of the basic needs in life, and consistency in the achievement of human health, and other related human needs. Furthermore, the availability of quality drinking water is necessary in order to successfully produce food or raw materials for the production of other products in the secondary sector. For example, a quality drinking water is necessary in the livestock industry so that there will be quality produced products that can be readily used in the processing industry. The processing industry on the other hand would require availability of clean and excellent water supply as integral component of the production of high quality standard processed foods. The above illustrations just simply depict the importance of drinking water in the production of raw materials and down to the processing and production of secondary product offerings.

SCHOOL LEADERS RESEARCH Essay Example | Topics and Well Written Essays - 3000 words

SCHOOL LEADERS RESEARCH - Essay Example 1.1 Rationale for Selecting the Article Written by Smyth (2011) School empowerment is all about being able to strengthen the decision-making power of the educational institution through the use of either administrative strategies or pedagogy (Di Gropello, 2006, p. 4). In line with this, there is a very close relationship between school empowerment and the need to become a self-managing school in the sense that the process of creating a self-managing school is necessary in terms of empowering the school. One of the main reasons for choosing the article written by Smyth (2011) is that the author decided to focus his study in determining factors that can negatively affect the ability of the school personnel to create a self-managing school. ... , even though the author clearly stated the main purpose of the study as part of the introduction, it would have been better if the author has written the article with a well-defined abstract that use subheadings such as purpose, methodology, findings, research implications, practical implications, and originality. With the use of subheadings, the readers can easily read and understand what the author intends to present to the readers. 2.2 Assumptions A research paradigm is usually composed of either assumptions, propositions, or a collection of concepts (Bogdan & Biklen, 1998, p. 22). In a highly reliable research study, the author’s assumption should be clearly stated because it can be used as a guide on how the researcher would direct the main focus of the research study. Likewise, the kind of research method that will be used in the research study is highly dependent on the research assumption (Punch, 2009, p. 15). Most of the research study assumptions are based on a wide -range of existing theories (Cook & Campbell, 1979, p. 24). For instance, when conducting a research study on school leaders, the research study assumptions can either be based on the point-of-views of the local citizens, school management system, educational leadership, or school administration (Eacott, 2011b). Since most of the research study assumptions are based on a wide-range of existing theories (Cook & Campbell, 1979, p. 24), creating a set of research study assumptions is important because it can be use to guide the researcher in search for some concrete and/or scientifically tested information to support his own research study assumptions (McMillan, 2011). In the article written by Smyth (2011), the author was able to clearly justify the reasons for his claim or assumption. Although

The influence of central banks' interventions on the level and Essay

The influence of central banks' interventions on the level and volatility of foreign exchange rate - Essay Example Furthermore, in a number of nations the central bank is essentially responsible for determination of the foreign exchange rate. The exchange rate volatility took prominent shape since the collapse of the Bretton Wood fixed exchange rate system (Galati and Melick, 2002). Since exchange rate plays an important role in supporting international trade, its volatility is seen as a hindrance. Therefore, central banks often make strong effort for minimising the volatility or it’s after effect on business. However, there are several analyses which suggest that central bank’s intervention tend to increase volatility of foreign exchange market while the bank tends to witness losses while managing the volatility. The paper assesses the impact of the central bank intervention on volatility of exchange rate. Meanwhile, various relevant factors such as types of exchange rate systems, potential scope of resource wastage and intended and unwanted impact of intervention policies have been discussed briefly. The foreign exchange market is the prevalent financial market across the globe. Foreign exchange trading is referred to transacting of one currency in exchange of others. Trading of currencies generally takes place in the form of bank transfers and bank deposit. Except for tourism and physical purchases, physical transfer and exchange of currencies rarely happens. The exchange rate system is an imperative characteristic of foreign exchange market and that of the global economic policy. Based on conventional models, exchange rate system can be classified as fixed exchange rate and floating exchange rate. Fixed exchange rate, which is also known as pegged exchange rate, is referred to the arrangement of price determination where rate of one currency (national currency) with respect to other foreign currencies is kept fixed by means of government intervention. Fixed exchange rate has been considered favourable when two or more countries experience similar

The novel The Da Vinci Code by Dan Brown Essay Example for Free

The novel The Da Vinci Code by Dan Brown Essay Dan Brown prepares the reader for the rest of the novel, The Da Vinci Code with a puzzling yet interesting prologue. The Da Vinci Code is the fourth novel by Dan Brown, a famous author who released his first novel Digital Fortress in 1998. I chose to read The Da Vinci Code because it has received excellent reviews and it explains philosophical concepts from the time of Jesus Christ. I was drawn to The Da Vinci Code as a film was released in 2006 and the first two novels had been excellent. I was attracted to the novel because the title gives a spooky and suspicious sense of atmosphere. The series is based in the modern world and the novels are based on code- breaking skills giving them a thriller nature. In this essay, I am going to be explaining anything confusing or puzzling that crop up in the prologue and how this may affect the readers sense of curiosity. Unlike the other novels, The Da Vinci Code begins with an action scene, leaving the reader curious. The title The Da Vinci Code indicates another code- breaking plot however it leaves readers wondering, what code is to be solved? The word code is quite vague and could imply there is a secret waiting to be unleashed. Dan Brown added the phrase The Da Vinci before code. Da Vinci is short for Leonardo da Vinci, a great painter, inventor and writer. A reader will be aware of this because Da Vinci is famous. Even though Da Vinci was regarded as a skilled engineer, none of his works linked to puzzles and codes. The title therefore leaves the reader in a puzzling state of confusion and the front cover shows a small portion of The Mona Lisa by Leonardo da Vinci, confirming that Da Vinci is linked to the novel. Dan Brown has cleverly constructed the title and cover, leaving readers debating over the plot, causing them to feel curious, drawing readers in to read the book. The first sentence appeals to our sense of sight and causes readers to feel curious. The sentence reads: Renowned curator Jacques Sauniere staggered through the vaulted archway of the museums Grand Gallery. The sentence introduces a character, Curator Jacques Sauniere and this causes the reader to question, who is Jacques Sauniere? Why is he the curator of the museum and how is he famous? The second part of the sentence involves the curator staggering through a vaulted archway. This implies many possibilities: The curator could have simply tripped or he might have even been chased. This leaves readers in suspense because they would want to know who is chasing the curator and why. The word staggered stresses a sense of trouble. This is quite powerful because it is immediate and causes the reader to feel startled. The sentence as a whole allows readers to visualise the setting and confirms that the curator is in a museum; however the gallery of the museum was described as grand, indicating that the museum is well known, making readers wonder if there is trouble in the building. And if so, why have security guards not arrived at the scene. Being a prologue, Dan Brown does not introduce many of the main characters until the 1st chapter, however two characters are introduced. Brown introduces the Museums curator Jacques Sauniere. He is depicted to be famous, because he was described as renowned and readers visualise Sauniere to be weak and helpless as he found it extremely difficult to heave a masterpiece. However, we assume Sauniere is part of a hidden organization, possessing a truth: If I die, the truth will be lost for ever. The quote evokes readers sense of curiosity, therefore causing them to wonder: Who is Sauniere? The second character, Albino, is after the curator and eventually captures him. He was broad and tall, with ghost- pale skin and thinning white hair. His irises were pink with dark red pupils, Albino is pictured as a dark, suspicious character causing readers to be inquisitive. Readers feel sorry for the curator when he is shot by Albino for lying about not knowing the secret. Albino leaves quickly, illustrating that he will return in the novel. Brown was correct in leaving out the many of the main characters because the prologue was there to leave readers in suspense and to create background information for the novel, preparing the reader. Dan Brown allows the reader to know that the book belongs to the thriller genre: As he had anticipated, a thundering iron gate fell nearby, barricading the entrance to the suite. The parquet floor shook. Far off, an alarm began to ring. The sentence uses a number of powerful words, attracting the reader. Thundering Iron Gate fell nearby allow readers to visualise a gigantic, grand security system. From the phrase, you want to know why the Iron Gate fell and so this starts to quiz readers. Barricading stresses a sense of foreboding because readers dont understand why the curator would want to lock himself in a museum, leaving readers in suspense as they wonder if there is a purpose behind his action, contributing to the hunch that he could be in danger. Far off, an alarm began to ring give readers the impression that there is a robbery occurring although the assumption is not true. Other ways in which the author allows the reader to identify that the book belongs to the thriller genre is using words such as thundering, roared and wincing. These words all suggest a thriller due to the fact that it allows readers to visualise the scene, appealing to their sense of sight. The Gun roared is portrays a murder scene confirming the genre however, readers develop an idea that a mystery is being conjured. In the prologue, we are told of a mysterious character however the description is quite vague adding to the mystery. All of the quotes and words above allow readers to know the genre of the book, preparing them for the rest of the novel. Throughout the prologue, readers will feel confused. Immediately introducing the curator, Jacques Sauniere, the prologue bemuses readers, causing them to wonder and question. However, Brown introduces Sauniere describing him as renowned. The word is powerful in many contexts: It allows readers to know that he is famous but more importantly, it makes them feel that they already know the curator, allowing questions to leave readers minds. Albino, the ghostly figure in the prologue causes reader to be curious because they do not know who he is and why he is after the curator. This is considered effective because it creates suspense for readers. Albino mentions something: Now tell me where it is. The phrase causes reader to guess what this particular item is, perplexing readers as well as leaving them in suspense. Calling the item it gives it importance and classifies that the thing is special. Towards the end of the prologue, we are told that the item is actually a secret, intriguing readers, as they want to know what the secret holds. Although there are many other phrases and sentences that leave you anxious, you are still given a complete plot of the prologue because the setting is well-described. The author did this intently because it triggers readers imagination. Confusion is effective in the introduction because the author has time to pick up on topics which are necessary at a particular point and then build up on them when they are needed later, creating suspense, preparing readers for the rest of the novel. The Last two sentences of the prologue are very powerful, concluding the prologue efficiently: Wincing in pain, he summoned all of his faculties and strength. The desperate task before him, he knew, would require every remaining second of his life. Wincing, faculties and desperate are all effective words used in the last two lines and they are excellent at describing the curator, giving readers a visual image of him. Wincing justifies that the curator is extremely weak and adding in pain emphasises the fact that he is going to die. We are told that he has a task to do before he dies, however we do not know what it is, adding to the suspense. Readers are drawn to the ending phrase, every remaining second of his life because it denotes that the task is significant for the events in the novel. You feel sorry for the curator because he is innocent and didnt deserve to be shot whereas you feel vengeful towards Albino. The sentence ends abrupt, asking readers many questions. They want to know: Is Sauniere dead? What is the desperate task he wanted to complete and what has happened to Albino? A cliff-hanger is formed by ending abruptly, evoking readers sense of curiosity. Therefore, the last two sentences of the prologue are successful at preparing the reader for the rest of the novel. The introduction to The Da Vinci Code is brilliant for preparing the reader for the rest of the novel by setting a good theme. The introduction leaves you in suspense, generating an urge for you to read on. All aspects of the prologue contribute to its excellence. The prologue is kept as simplistic as possible, providing background knowledge for readers. I have deeply enjoyed the book so far and I can say that readers will continue to feel a sense of thrill as they progress through the novel.