The Atom Detectives
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Neutron Stars
Chandra X-Ray Observatory X-Ray Astronomy Field Guide Neutron Stars Ordinary matter, or the stuff we and everything around us is made of, consists largely of empty space. Even a rock is mostly empty space. This is because matter is made of atoms. An atom is a cloud of electrons orbiting around a nucleus composed of protons and neutrons. The nucleus contains more than 99.9 percent of the mass of an atom, yet it has a diameter of only 1/100,000 that of the electron cloud. The electrons themselves take up little space, but the pattern of their orbit defines the size of the atom, which is therefore 99.9999999999999% Chandra Image of Vela Pulsar open space! (NASA/PSU/G.Pavlov et al. What we perceive as painfully solid when we bump against a rock is really a hurly-burly of electrons moving through empty space so fast that we can't see—or feel—the emptiness. What would matter look like if it weren't empty, if we could crush the electron cloud down to the size of the nucleus? Suppose we could generate a force strong enough to crush all the emptiness out of a rock roughly the size of a football stadium. The rock would be squeezed down to the size of a grain of sand and would still weigh 4 million tons! Such extreme forces occur in nature when the central part of a massive star collapses to form a neutron star. The atoms are crushed completely, and the electrons are jammed inside the protons to form a star composed almost entirely of neutrons. -
The Practice of Chemistry Education (Paper)
CHEMISTRY EDUCATION: THE PRACTICE OF CHEMISTRY EDUCATION RESEARCH AND PRACTICE (PAPER) 2004, Vol. 5, No. 1, pp. 69-87 Concept teaching and learning/ History and philosophy of science (HPS) Juan QUÍLEZ IES José Ballester, Departamento de Física y Química, Valencia (Spain) A HISTORICAL APPROACH TO THE DEVELOPMENT OF CHEMICAL EQUILIBRIUM THROUGH THE EVOLUTION OF THE AFFINITY CONCEPT: SOME EDUCATIONAL SUGGESTIONS Received 20 September 2003; revised 11 February 2004; in final form/accepted 20 February 2004 ABSTRACT: Three basic ideas should be considered when teaching and learning chemical equilibrium: incomplete reaction, reversibility and dynamics. In this study, we concentrate on how these three ideas have eventually defined the chemical equilibrium concept. To this end, we analyse the contexts of scientific inquiry that have allowed the growth of chemical equilibrium from the first ideas of chemical affinity. At the beginning of the 18th century, chemists began the construction of different affinity tables, based on the concept of elective affinities. Berthollet reworked this idea, considering that the amount of the substances involved in a reaction was a key factor accounting for the chemical forces. Guldberg and Waage attempted to measure those forces, formulating the first affinity mathematical equations. Finally, the first ideas providing a molecular interpretation of the macroscopic properties of equilibrium reactions were presented. The historical approach of the first key ideas may serve as a basis for an appropriate sequencing of -
The History of the Concept of Element, with Particular Reference to Humphry Davy
The Physical Sciences Initiative The history of the concept of element, with particular reference to Humphry Davy One of the problems highlighted when the recently implemented chemistry syllabus was being developed was the difficulty caused by starting the teaching of the course with atoms. The new syllabus offers a possible alternative teaching order that starts at the macroscopic level, and deals with elements. If this is done, the history of the idea of elements is dealt with at a very early stage. The concept of element originated with the ancient Greeks, notably Empedocles, who around 450 BC defined elements as the basic building blocks from which all other materials are made. He stated that there were four elements: earth, air, fire and water. Substances were said to change when elements break apart and recombine under the action of the forces of strife and love. Little progress was made in this area until the seventeenth century AD. The fruitless attempts of the alchemists to change base metals such as lead into gold and to find the “elixir of life” held back progress, although much chemical knowledge and expertise was gained. In 1661, 1 The Physical Sciences Initiative The Physical Sciences Initiative Robert Boyle defined an element as a substance that cannot be broken down into simpler materials. He cast doubt on the Greek elements, and provided a criterion for showing that a material was not an element. Robert Boyle Many elements were discovered during the next 100 years, but progress was delayed by the phlogiston hypothesis. According to this hypothesis, when a substance was burned it lost a substance called phlogiston to the air. -
Hemistry N E W S L E T T E R
University of Michigan Chemistry N E W S L E T T E R Letter from the Chair I am pleased to send greetings and to fullerene, was a very engaging keynote Contents highlight the activities of the Chemistry speaker for this event. Before his talk, the Department this past year. The Depart- Department was awarded a 2006 Citation Letter from the Chair ........................ 1 ment is continuing to make enormous for Chemical Breakthroughs from the Di- New Faculty ..................................... 3 strides towards accomplishing its goal of vision of the History of Chemistry of the becoming one of the top Chemistry De- American Chemical Society in recognition Faculty News.................................... 4 partments in the nation. The most recent of work by Moses Gomberg. Additionally, I 150th Birthday ...................................4 US News and World Report ranking of have enjoyed meeting departmental alumni Graduate Program News Chemistry Departments listed Michigan and alumnae as well as prospective faculty as 16th in the nation; the analytical cluster candidates at the University of Michigan Graduate Awards .......................... 7 was ranked 9th, biochemistry 13th, organic reception that is held at every American Graduate Degrees........................ 10 th th 13 , and inorganic 15 . These are the Chemical Society National meeting. Please GS Council News .........................12 highest rankings for these clusters in many plan on attending this reception at the next years. We anticipate that our standing in ACS meeting. Undergraduate Program News the community will continue to rise, in REU Program ...............................12 Over the past year the department has view of the tremendous success that we recruited Dr. Anne McNeil, an outstand- Undergraduate Awards ............... -
Historical Development of the Periodic Classification of the Chemical Elements
THE HISTORICAL DEVELOPMENT OF THE PERIODIC CLASSIFICATION OF THE CHEMICAL ELEMENTS by RONALD LEE FFISTER B. S., Kansas State University, 1962 A MASTER'S REPORT submitted in partial fulfillment of the requirements for the degree FASTER OF SCIENCE Department of Physical Science KANSAS STATE UNIVERSITY Manhattan, Kansas 196A Approved by: Major PrafeLoor ii |c/ TABLE OF CONTENTS t<y THE PROBLEM AND DEFINITION 0? TEH-IS USED 1 The Problem 1 Statement of the Problem 1 Importance of the Study 1 Definition of Terms Used 2 Atomic Number 2 Atomic Weight 2 Element 2 Periodic Classification 2 Periodic Lav • • 3 BRIEF RtiVJiM OF THE LITERATURE 3 Books .3 Other References. .A BACKGROUND HISTORY A Purpose A Early Attempts at Classification A Early "Elements" A Attempts by Aristotle 6 Other Attempts 7 DOBEREBIER'S TRIADS AND SUBSEQUENT INVESTIGATIONS. 8 The Triad Theory of Dobereiner 10 Investigations by Others. ... .10 Dumas 10 Pettehkofer 10 Odling 11 iii TEE TELLURIC EELIX OF DE CHANCOURTOIS H Development of the Telluric Helix 11 Acceptance of the Helix 12 NEWLANDS' LAW OF THE OCTAVES 12 Newlands' Chemical Background 12 The Law of the Octaves. .........' 13 Acceptance and Significance of Newlands' Work 15 THE CONTRIBUTIONS OF LOTHAR MEYER ' 16 Chemical Background of Meyer 16 Lothar Meyer's Arrangement of the Elements. 17 THE WORK OF MENDELEEV AND ITS CONSEQUENCES 19 Mendeleev's Scientific Background .19 Development of the Periodic Law . .19 Significance of Mendeleev's Table 21 Atomic Weight Corrections. 21 Prediction of Hew Elements . .22 Influence -
The Development of the Periodic Table and Its Consequences Citation: J
Firenze University Press www.fupress.com/substantia The Development of the Periodic Table and its Consequences Citation: J. Emsley (2019) The Devel- opment of the Periodic Table and its Consequences. Substantia 3(2) Suppl. 5: 15-27. doi: 10.13128/Substantia-297 John Emsley Copyright: © 2019 J. Emsley. This is Alameda Lodge, 23a Alameda Road, Ampthill, MK45 2LA, UK an open access, peer-reviewed article E-mail: [email protected] published by Firenze University Press (http://www.fupress.com/substantia) and distributed under the terms of the Abstract. Chemistry is fortunate among the sciences in having an icon that is instant- Creative Commons Attribution License, ly recognisable around the world: the periodic table. The United Nations has deemed which permits unrestricted use, distri- 2019 to be the International Year of the Periodic Table, in commemoration of the 150th bution, and reproduction in any medi- anniversary of the first paper in which it appeared. That had been written by a Russian um, provided the original author and chemist, Dmitri Mendeleev, and was published in May 1869. Since then, there have source are credited. been many versions of the table, but one format has come to be the most widely used Data Availability Statement: All rel- and is to be seen everywhere. The route to this preferred form of the table makes an evant data are within the paper and its interesting story. Supporting Information files. Keywords. Periodic table, Mendeleev, Newlands, Deming, Seaborg. Competing Interests: The Author(s) declare(s) no conflict of interest. INTRODUCTION There are hundreds of periodic tables but the one that is widely repro- duced has the approval of the International Union of Pure and Applied Chemistry (IUPAC) and is shown in Fig.1. -
TEK 8.5C: Periodic Table
Name: Teacher: Pd. Date: TEK 8.5C: Periodic Table TEK 8.5C: Interpret the arrangement of the Periodic Table, including groups and periods, to explain how properties are used to classify elements. Elements and the Periodic Table An element is a substance that cannot be separated into simpler substances by physical or chemical means. An element is already in its simplest form. The smallest piece of an element that still has the properties of that element is called an atom. An element is a pure substance, containing only one kind of atom. The Periodic Table of Elements is a list of all the elements that have been discovered and named, with each element listed in its own element square. Elements are represented on the Periodic Table by a one or two letter symbol, and its name, atomic number and atomic mass. The Periodic Table & Atomic Structure The elements are listed on the Periodic Table in atomic number order, starting at the upper left corner and then moving from the left to right and top to bottom, just as the words of a paragraph are read. The element’s atomic number is based on the number of protons in each atom of that element. In electrically neutral atoms, the atomic number also represents the number of electrons in each atom of that element. For example, the atomic number for neon (Ne) is 10, which means that each atom of neon has 10 protons and 10 electrons. Magnesium (Mg) has an atomic number of 12, which means it has 12 protons and 12 electrons. -
Centripetal Force Is Balanced by the Circular Motion of the Elctron Causing the Centrifugal Force
STANDARD SC1 b. Construct an argument to support the claim that the proton (and not the neutron or electron) defines the element’s identity. c. Construct an explanation based on scientific evidence of the production of elements heavier than hydrogen by nuclear fusion. d. Construct an explanation that relates the relative abundance of isotopes of a particular element to the atomic mass of the element. First, we quickly review pre-requisite concepts One of the most curious observations with atoms is the fact that there are charged particles inside the atom and there is also constant spinning and Warm-up 1: List the name, charge, mass, and location of the three subatomic circling. How does atom remain stable under these conditions? Remember particles Opposite charges attract each other; Like charges repel each other. Your Particle Location Charge Mass in a.m.u. Task: Read the following information and consult with your teacher as STABILITY OF ATOMS needed, answer Warm-Up tasks 2 and 3 on Page 2. (3) Death spiral does not occur at all! This is because the centripetal force is balanced by the circular motion of the elctron causing the centrifugal force. The centrifugal force is the outward force from the center to the circumference of the circle. Electrons not only spin on their own axis, they are also in a constant circular motion around the nucleus. Despite this terrific movement, electrons are very stable. The stability of electrons mainly comes from the electrostatic forces of attraction between the nucleus and the electrons. The electrostatic forces are also known as Coulombic Forces of Attraction. -
Graduation 2013. Wednesday 17 July 2013 the University of Sheffield
Graduation 2013. Wednesday 17 July 2013 The University of Sheffield Your graduation day is a special day for you and your family, a day for celebrating your achievements and looking forward to a bright future. As a graduate of the University of Sheffield you have every reason to be proud. You are joining a long tradition of excellence stretching back more than 100 years. The University of Sheffield was founded with the amalgamation of the School of Medicine, Sheffield Technical School and Firth College. In 1905, we received a Royal Charter and Firth Court was officially opened by King Edward VII and Queen Alexandra. At that time, there were 363 students reading for degrees in arts, pure science, medicine and applied science. By the time of our centenary, there were over 25,000 students from more than 100 countries, across 70 academic departments. Today, a degree from Sheffield is recognised all over the world as a hallmark of academic excellence. We are proud of our graduates and we are confident that you will make a difference wherever you choose to build your future. With every generation of graduates, our university goes from strength to strength. This is the original fundraising poster from 1904/1905 which helped raise donations for the University of Sheffield. Over £50,000 (worth more than £15 million today) was donated by steelworkers, coal miners, factory workers and the people of Sheffield in penny donations to help found the University. A century on, the University is now rated as one of the top world universities – according to the Shanghai Jiao Tong Academic Ranking of World Universities. -
Of the Periodic Table
of the Periodic Table teacher notes Give your students a visual introduction to the families of the periodic table! This product includes eight mini- posters, one for each of the element families on the main group of the periodic table: Alkali Metals, Alkaline Earth Metals, Boron/Aluminum Group (Icosagens), Carbon Group (Crystallogens), Nitrogen Group (Pnictogens), Oxygen Group (Chalcogens), Halogens, and Noble Gases. The mini-posters give overview information about the family as well as a visual of where on the periodic table the family is located and a diagram of an atom of that family highlighting the number of valence electrons. Also included is the student packet, which is broken into the eight families and asks for specific information that students will find on the mini-posters. The students are also directed to color each family with a specific color on the blank graphic organizer at the end of their packet and they go to the fantastic interactive table at www.periodictable.com to learn even more about the elements in each family. Furthermore, there is a section for students to conduct their own research on the element of hydrogen, which does not belong to a family. When I use this activity, I print two of each mini-poster in color (pages 8 through 15 of this file), laminate them, and lay them on a big table. I have students work in partners to read about each family, one at a time, and complete that section of the student packet (pages 16 through 21 of this file). When they finish, they bring the mini-poster back to the table for another group to use. -
Rutherford's Atomic Model
CHAPTER 4 Structure of the Atom 4.1 The Atomic Models of Thomson and Rutherford 4.2 Rutherford Scattering 4.3 The Classic Atomic Model 4.4 The Bohr Model of the Hydrogen Atom 4.5 Successes and Failures of the Bohr Model 4.6 Characteristic X-Ray Spectra and Atomic Number 4.7 Atomic Excitation by Electrons 4.1 The Atomic Models of Thomson and Rutherford Pieces of evidence that scientists had in 1900 to indicate that the atom was not a fundamental unit: 1) There seemed to be too many kinds of atoms, each belonging to a distinct chemical element. 2) Atoms and electromagnetic phenomena were intimately related. 3) The problem of valence (원자가). Certain elements combine with some elements but not with others, a characteristic that hinted at an internal atomic structure. 4) The discoveries of radioactivity, of x rays, and of the electron Thomson’s Atomic Model Thomson’s “plum-pudding” model of the atom had the positive charges spread uniformly throughout a sphere the size of the atom with, the newly discovered “negative” electrons embedded in the uniform background. In Thomson’s view, when the atom was heated, the electrons could vibrate about their equilibrium positions, thus producing electromagnetic radiation. Experiments of Geiger and Marsden Under the supervision of Rutherford, Geiger and Marsden conceived a new technique for investigating the structure of matter by scattering particles (He nuclei, q = +2e) from atoms. Plum-pudding model would predict only small deflections. (Ex. 4-1) Geiger showed that many particles were scattered from thin gold-leaf targets at backward angles greater than 90°. -
Pioneers of Atomic Theory Darius Bermudez Discoverers of the Atom
Pioneers of Atomic Theory Darius Bermudez Discoverers of the Atom Democritus- Greek Philosopher proposed that if something was divided enough times, eventually the particles would be too small to divide any further. Ex: Identify this Greek philosopher who postulated that if an object was divided enough times, there would eventually be small particles that could not be divided any further. Discoverers of the Atom John Dalton- English chemist who made the “billiard ball” atom model. First to prove that rainfall was a result of temperature change. He was the first scientist after Democritus to build on atomic theory. He also created a law on partial pressures. Common Clues: Partial pressures, pioneer of atomic theory, and temperature change causes rainfall. The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. Discoverers of the Atom J.J. Thomson- English Scientist who discovered electrons through a cathode. Made the “plum pudding model” with Lord Kelvin (Kelvin Scale) which stated that negative charges were spread about a positive charged medium, making atoms neutral. Common Clues: Plum pudding, Electrons had negative charges, disproved by either Rutherford or Mardsen and Geiger The image cannot be displayed.