Washington, CHEM 142

Excerpt: ... Lecture #2 The Structure of Atom Chemistry 142 Younan Xia, Instructor Autumn Quarter, 2006 Outline 1. The three key subatomic particles 2. Crookes cathode-ray tube (CRT) 3. J. J. Thomson experiment 4. Millikan oil-drop experiment 5. Rutherford scattering experiment 6. The modern view of atomic structure Three Key Subatomic Particles Notes: mass of e- is tiny relative to p+ and n0. p+, n0 have same mass (almost). e-, p+ have same charge, opposite sign. Cathode-Ray Tube (CRT) (Sir William Crookes, 1880) Phosphors for color display ZnS:Ag La2O2S:Tb Y2O2S:Eu blue (460 nm) green (543 nm) red (627 nm) J. J. Thomson Experiment (John Joseph Thomson, Cambridge University, 1898) charge to mass ratio Millikan Oil Drop Experiment (Robert Millikan, University of Chicago, 1909) charge and mass Rutherford Scattering Experiment (Ernest Rutherford, Cambridge University, 1911) the nuclear atom model General Features of the Atom Moving electron cloud surrounds nucleus. Almost all the mass is in the nucleus. Di ...

Emory, CHEM 141

Excerpt: ... Please refer to the General Study Sheet Post for information regarding the exams THE COMPONENTS OF MATTER CHAPTER 2 INTRODUCTION The history of the modern atomic theory spans nearly 2000 years. However, it is only in the last 200 years that there has been a good understanding of the atom and even still new discoveries about microscopic atomic structure are being made. It is important as a scientist to know the major people involved in discovery and understand the experiments performed which led to our current understanding of the atom. Names and achievements of the scientists who have helped to lay the foundation of our knowledge are important to know to allow for a historical perspective of our understanding. With the discovery of the subatomic particles such as the electron, proton, and neutron we can explain isotopes, bonding, and many other atomic properties. Further, knowledge of isotopes helps us to understand why atoms do not have integral masses the measured atomic mass of an element is a weigh ...

Laurentian, CHEM 2200

Excerpt: ... ble Health Note: Some Important Trace Elements in the Body Career Focus: Optician 2.3 The Atom Explore Your World: Repulsion and Attraction 2.4 Atomic Number and Mass Number 2.5 Isotopes and Atomic Mass 2.6 Electron Energy Levels Explore Your World: Light Released from Candy Environmental Note: Biological Reactions to UV Light 2.7 Subshells and Orbitals 2.8 Electron Configurations Chapter Summary and Demonstrations 1. Elements and Atoms The elements and their corresponding symbols are described for commonly occurring element and elements prevalent in biological systems. The atom is discussed in terms of protons, neutrons and electrons. The subatomic particles of the atom are described and related to atomic number and atomic mass. Examples of isotopes of an element and their contribution to the weighted average atomic mass of an element are discussed. Demonstration: Tear up a piece of paper into smaller and smaller pieces. Ask students how many times they need to do this to get to atoms. Have a student with a ...

North Texas, COE 1252

Excerpt: ... s of energy are emitted when the electron moves from an excited state back to the ground state. The weakness of the Bohr Model lies with the energy levels. There is no explanation for the fine line spectrum that appears along with the strong spectral lines. The Bohr model does not account for the existence of more than one electron, thus does not explain the configuration of atoms other than the hydrogen atom. The model also fails to explain molecular bonding. The Bohr model has some limited value, but is more inconsistent than consistent with experimental information collected on atoms. According to modern theories the atom can best be described mathematically. Models and analogies can still be used, however, on a limited basis. Exact positions and motions of subatomic particles cannot be measured and are thus unknown. An electron orbital is a volume configuration that denotes where there is the probability of finding an electron. These orbitals appear as fuzzy electron clouds. Most of an atom is empty spa ...

American River, CHEM 400-401

Excerpt: ... ted his famous Oil-Drop Experiment: From this experiment, Millikan obtained the actual charge on an electron, 1.60x10-19 C. And from this charge and Thomson's charge/mass ratio, the exact mass of an electron was calculated to be 9.10x10-28 g. So from these experiments, scientists deduced that atoms were made up of even smaller subatomic particles , one of which was the electron. Since electrons have a negative charge, while atoms are neutral, scientists also realized that there had to be at least 1 more subatomic particle with a positive charge. But where was this particle in the atom and what did it look like? A popular model of the atom at this time was Thomson's Plum Pudding Model: Thomson knew that the mass of an electron was very tiny compared to the mass of the atom, so his model is based on his speculation that they also took up very little of an atom's volume. Although this model seemed logical, it was blown out of the water by a serendipitous experiment conducted in ...

Saginaw Valley, CHEM 111

Excerpt: ... 75.77% of the atoms are 35Cl and 24.23% are atoms of 37Cl. The accurately measured atomic mass of 35Cl is 34.9689 u and that of 37Cl is 36.9659 u. From these data, calculate the average atomic mass of chlorine. Lecture notes for Chem 111 by Dr. Alan Zombeck 10 Lecture notes for Chem 111 by Dr. Alan Zombeck 11 Atoms are composed of subatomic particles Protons, neutrons, and electrons are subatomic particles Modern view of atomic structure Atoms are composed of protons/neutrons in a nucleus, with electrons orbiting around the nucleus Notice mass of an electron vs mass of a proton or neutron Table 1.3 Properties of subatomic particles Key Historical scientific discoveries for determining the structure of the atom For your reading entertainment, see Facets of Chemistry 1.1 on pages 21-23 1897 JJ Thompson's cathode ray tube determined charge/mass ratio of electrons 1909 Millikan oil drop experiment determined the charge for a single electron 1915 Rutherford discovers the atomic nucl ...

Kentucky, CHE 105

Excerpt: ... August 30, 2006 Chemistry Lecture Notes Polyatomic ions memorize Naming compounds Atoms, Molecules & Ions Dalton's Atomic Theory first developed by Dalton Dalton's work marked the beginning of modern chemistry and has four statements. o Elements are composed of small particles called atoms. Atom means indivisible cannot be broken down into anything smaller o All atoms of a given element are identical. The atoms of one element are different from all other elements. o Compounds are composed of atoms of more than one element. o A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction. The structure of the atom Atoms were discovered to not be indivisible but to exist of subatomic particles Electron, proton, neutron How were they discovered? The electron o Cathode ray tube o o When the magnetic, electrical fields were applied, different movements of the beam o Showed that electrons had electrical and magnetic properties E ...

UNL, CHEM 105

Excerpt: ... Introduction Keys to the Study of Chemistry 1 Welcome to CHEM 105! This lecture will cover: 1.1 Online Homework 1.2 How to Study Chemistry 1.3 What is Chemistry? 1.4 The 3 Languages of Chemistry 2 3 How to Study Chemistry Interactive science Read Chapter Take Reading Comprehension on EDU View the PowerPoint presentation Take the Chapter Assessment on EDU Read the accompanying lab Take the Prelab on EDU Perform the lab Submit the lab report on Blackboard Do end of chapter homework See List of Cool Websites on Blackboard 4 Seek additional practice What is Chemistry? matter its properties Chemistry is the study of the changes that matter undergoes AND the energy associated with these changes 5 What is a Chemical? Textbook doesnt define Matter Anything that has mass and takes up space Chemical Anything made up of atoms http:/www.chemicalfreekids.com/ What isnt a chemical? Subatomic particles Energy Thoughts, feelings 6 The ...

Cornell, ASTRO 1102

Excerpt: ... Lecture #7: Radiation and Spectra II How is light absorbed and emitted? Models of Atomic Structure. Formation of Spectral Lines. Doppler Shift. The Main Point Astronomers use spectroscopy, the study of the interaction of light and matter, to determine what planetary surfaces and atmospheres are made of. Applications in Solar System Studies Detecting gaseous phases (atmospheres, stars). Detecting solid phases (ices, minerals). Astro 102/104 1 Astro 102/104 2 How do light and matter interact? The interaction occurs at the atomic scale. Therefore, understanding the interaction means understanding the atom. But the realm of the atom is at a scale that is completely outside our intuitive experience. So scientists have devised models of the atom, to try to grasp what's going on. Subatomic Particles J.J. Thomson discovered the existence of electrons in 1897. He used a cathode ray tube to show that particles appeared to be carrying negative charge. Since atoms are ...

Wisconsin Milwaukee, CHEM 185

Excerpt: ... Chapter 2 Classification of matter Elements Compounds Atoms Molecules Mixtures (homogeneous and heterogeneous, solutions) Physical properties Intensive properties Extensive properties (depend on mass of the sample) Chemical properties Physical changes versus chemical changes (chemical reaction) Law of conservation of mass Energy Definition of energy (Capacity for doing work or causing change) Different types of energy (table 2.1 p.22) Law of conservation of energy Chemical elements Symbols for elements (the most important 8 elements/non-metals with single letter symbols (p.27) 7 diatomic elements (p.27) Formulas of simple molecular compounds (p.28, table 2.3) Chemical reactions (reactantsproducts) Chapter 3 John Daltons atomic theory 4 postulates of Daltons theory (p.40) Law of conservation of matter Law of definite proportions Structure of the atom Subatomic particles (protons, neutrons, electrons including their ...

IUP, CH 101

Excerpt: ... Learning Objectives - Blei & Odian Chapter 2 (5/18/2009) Special Notes Assigned Problems: 2.4, 2.7, 2.10, 2.12, 2.13, 2.14. Turn in the assigned problems no later than 5 PM, Monday, September 17 at my office: Weyandt Hall 239C. You should also learn the IUPAC (International Union of Pure And Applied Chemists) number system for periodic table groups. General Learning Objectives for Chapter 2 You should be able to describe the law of conservation of mass, the law of constant composition and Dalton's theory of matter. You should be able to describe the characteristics of all three major subatomic particles : protons, neutrons and electrons. You should be able to write the name or symbol of an element based on mass number and atomic number. You should be able to determine the number of protons, neutrons and electrons in an atom or ion. You should be able to identify and label all regions of the periodic table. You should be able to classify and element as a metal, nonmetal or metalloid. You sho ...

UC Davis, PSC 113

Excerpt: ... Proteins, DNA Subatomic Particles Notes: page 3 Compositional Levels do not reveal how the components at one level interact to produce the behavior and organization of things at a higher level. Thus, for example, merely knowing that a group is composed of individuals of a particular species (e.g., army ants, wild dogs, or humans), tells us very little about the social structure of the group or how the individuals develop in the context of the group. 1.B. Levels: Interactions Another meaning of Levels is the number, strength, and kinds of interactions among components at different levels of composition. The interactions of components at a given level constitute levels of organization. Organization often emerge from simple interactions of components as we saw with fall webworms and as we will see with army ants below. Example: Aggregation Rules Complex systems, however, are not limited to interactions (i.e., interactional complexity) with components at one level of compositional. For example, oxytocin, is a ...