DOCSLIB.ORG

5.1 Models of the Atom 5.1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
5.1 Models of the Atom 5.1 chem_TE_ch05.fm Page 127 Saturday, April 15, 2006 10:46 AM 5.1 Models of the Atom 5.1 1 FOCUS Connecting to Your World Aeronautical engineers use Guide for Reading wind tunnels and scale models to simulate and test the forces from the Objectives moving air on each proposed design. The scale model shown is a physical Key Concepts • What was inadequate about 5.1.1 Identify the inadequacies in model. However, not all models are physical. In Rutherford’s atomic model? fact, several theoretical models of the atom • What was the new proposal in the Rutherford atomic model. have been developed over the last few the Bohr model of the atom? 5.1.2 Identify the new proposal in • hundred years. In this section, you will What does the quantum mechanical model determine the Bohr model of the atom. learn about the currently accepted model about the electrons in an atom? 5.1.3 Describe the energies and of how electrons behave in atoms. • How do sublevels of principal energy levels differ? positions of electrons accord- Vocabulary ing to the quantum mechanical energy levels model. quantum 5.1.4 Describe how the shapes of The Development of Atomic Models quantum mechanical model So far in this textbook, the model for the atom consisted of protons and atomic orbital orbitals related to different neutrons making up a nucleus surrounded by electrons. After discovering Reading Strategy sublevels differ. the atomic nucleus, Rutherford used existing ideas about the atom and Using Prior Knowledge Before proposed an atomic model in which the electrons move around the you read, jot down three things nucleus, like the planets move around the sun. Rutherford’s model you already know about atoms. Guide for Reading explained only a few simple properties of atoms. It could not explain, for As you read the section, explain example, why metals or compounds of metals give off characteristic colors how what you already knew helped you learn something new. Build Vocabulary L2 when heated in a flame, or why objects—when heated to higher and higher temperatures—first glow dull red, then yellow, then white, as shown in Word Parts The word orbital was Figure 5.1. Rutherford’s atomic model could not explain the chemical coined by scientists in 1932 to describe properties of elements. Explaining what leads to the chemical properties of the space in which an atom has a high elements requires a model that better describes the behavior of electrons probability of being found. It is derived within atoms. from the word orbit, the path around the nucleus that electrons had been postulated to follow. Reading Strategy L2 Figure 5.1 Rutherford’s Relate Text and Visuals Have model fails to explain why students follow the Time Line in Figure objects change color when heated. As the temperature of 5.2 and explain why each model was this horseshoe is increased, it inadequate or incomplete. first appears black, then red, then yellow, and then white. The observed behavior could 2 INSTRUCT be explained only if the atoms in the iron gave off light in specific amounts of energy. A better atomic model was needed to explain this Have students study the photograph observation. and read the text. Ask, What are two Section 5.1 Models of the Atom 127 types of models? (physical and theo- retical) Why are models important? (You can test a model to see if your ideas or design are correct.) Section Resources The Development of Print Technology •Guided Reading and Study Workbook, •Interactive Textbook with ChemASAP, Atomic Models Section 5.1 Animation 5, Assessment 5.1 Relate L2 •Core Teaching Resources, Section 5.1 Compare the use of atomic models to Review develop the atomic theory to the use •Transparencies, T57 of physical or computer-generated models to design, develop, and test products, such as automobiles. Electrons in Atoms 127 chem_TE_ch05_IPL.fm Page 128 Wednesday, August 4, 2004 9:34 PM Path of a moving electron Section 5.1 (continued) – – – Sphere with The Bohr Model positive charge Discuss L2 throughout – – Prepare students for the expanded view of the atom by asking, What are the three major subatomic particles that – – Nucleus comprise an atom? (electron, proton, and neutron) What are the electrical Tiny, solid – Negatively charged sphere particle (electron) Rutherford charges associated with each of these Thomson Model Dalton Model particles? (electron, 1–; proton, 1+; neu- Model 1904 Hantaro Nagaoka, a Japanese 1911 New Zealand tron, 0) Describe the structure of the 1897 J.J. Thomson, a British physicist, suggests physicist Ernest nuclear atom in terms of the locations 1803 John Dalton scientist, discovers the electron. that an atom has a Rutherford finds that an pictures atoms as The later leads to his "plum- central nucleus. atom has a small, dense, of each of the subatomic particles. tiny, indestructible pudding" model. He pictures Electrons move in positively charged (Every atom, except hydrogen, consists of particles, with no electrons embedded in a sphere orbits like the rings nucleus. Electrons move of positive electrical charge. around the nucleus. a small dense nucleus composed of pro- internal structure. around Saturn. tons and neutrons that accounts for most of the mass of the atom. Hydrogen is an 1800 1805 1895 1900 1905 1910 exception because it has only one proton in its nucleus. Negatively charged elec- Figure 5.2 These illustrations The Bohr Model trons surround the nucleus and occupy show how the atomic model has changed as scientists learned Niels Bohr (1885–1962), a young Danish physicist and a student of Ruther- most of its volume. Electrons contribute more about the atom’s structure. ford, believed Rutherford’s model needed improvement. In 1913 Bohr little to the mass of an atom. ) changed Rutherford’s model to include newer discoveries about how the energy of an atom changes when it absorbs or emits light. He considered L2 the simplest atom, hydrogen, which has one electron. Bohr proposed Word Origins that an electron is found only in specific circular paths, or orbits, around The word quantity has the same the nucleus. The timeline in Figure 5.2 shows the development of atomic root as quantum and means “an models from 1800 to 1935. indefinite amount or number.” Each possible electron orbit in Bohr’s model has a fixed energy. The fixed energies an electron can have are called energy levels. The fixed energy levels of electrons are somewhat like the rungs of the ladder in Figure 5.3a. The lowest rung of the ladder corresponds to the lowest energy TEACHER Demo level. A person can climb up or down a ladder by going from rung to rung. Similarly, an electron can jump from one energy level to another. A person on a ladder cannot stand between the rungs. Similarly, the electrons in an Quantized Energy L2 atom cannot be between energy levels. To move from one rung to another, Purpose Students witness an example a person climbing a ladder must move just the right distance. To move of quantized energy. Word Origins from one energy level to another, an electron must gain or lose just the right amount of energy. In general, the higher an electron is on the energy Quantum comes from the Materials trumpet or trombone and a ladder, the farther it is from the nucleus. Latin word quantus, mean- player A quantum of energy is the amount of energy required to move an elec- ing “how much.” What tron from one energy level to another energy level. The energy of an elec- Procedure Have a student blow into a other commonly used trumpet or trombone. Challenge the English word comes from tron is said to be quantized. You have probably heard the term quantum this root? leap used to describe an abrupt change. The term originates from the ideas student to produce as many different found in the Bohr model of the atom. notes as he or she can without depressing any valves. Expected Outcomes It is not possible 128 Chapter 5 to play the entire scale without chang- ing the valve positions. In the open position, no matter how much energy is put in, the instrument will only Differentiated Instruction accept certain specific amounts of English Learners L2 energy and produce certain notes. The Have students make a poster to show the instrument accepts quantized pack- evolution of the model of the atom. Have ages of energy. them start with Dalton’s model and continue through all the modifications to the current quantum mechanical model. Have them include enough information to make the model clear and understandable. 128 Chapter 5 chem_TE_ch05.fm Page 129 Tuesday, April 18, 2006 10:09 AM An electron can gain The nucleus contains or lose energy by protons and neutrons. – changing its orbit. Use Visuals L1 Figure 5.3 Ask, What are the rungs in Electron the ladders compared to? (the energy – levels in atoms) How is the ladder in b + different from the ladder in a? (The The electron cloud is a visual model of the probable locations rungs are not evenly spaced. They get of electrons in an atom. The closer together nearer to the top.) probability of finding an electron is higher in the denser regions Nucleus of the cloud. Relate L2 When light shines on a fluorescent Bohr Electron Cloud Model Model material, its electrons absorb the 1923 French physicist Louis de Broglie energy and move to a higher energy 1913 In Niels proposes that moving 1926 Erwin Schrödinger 1932 James Chadwick, an level. Almost immediately, the mate- Bohr's model, the particles like electrons develops mathematical English physicist, confirms electron moves in have some properties of equations to describe the the existence of neutrons, rial begins to emit light as the elec- a circular orbit at waves.
Load more

Recommended publications
  • Atomic Orbitals
    Visualization of Atomic Orbitals Source: Robert R. Gotwals, Jr., Department of Chemistry, North Carolina School of Science and Mathematics, Durham, NC, 27705. Email: [email protected]. Copyright ©2007, all rights reserved, permission to use for non-commercial educational purposes is granted. Introductory Readings Where are the electrons in an atom? There are a number of Models - a description of models that look to describe the location and behavior of some physical object or electrons in atoms. It is important to know this information, as behavior in nature. Models it helps chemists to make statements and predictions about are often mathematical, describing the behavior of how atoms will react with other atoms to form molecules. The some event. model one chooses will oftentimes influence the types of statements one can make about the behavior – that is, the reactivity – of an atom or group of atoms. Bohr model - states that no One model, the Bohr model, describes electrons as small two electrons in an atom can billiard balls, rotating around the positively charged nucleus, have the same set of four much in the way that planets quantum numbers. orbit around the Sun. The placement and motion of electrons are found in fixed and quantifiable levels called orbits, Orbits- where electrons are or, in older terminology, shells. believed to be located in the There are specific numbers of Bohr model. Orbits have a electrons that can be found in fixed amount of energy, and are identified with the each orbit – 2 for the first orbit, principle quantum number 8 for the second, and so forth.
    [Show full text]
  • Chemical Bonding & Chemical Structure
    Chemistry 201 – 2009 Chapter 1, Page 1 Chapter 1 – Chemical Bonding & Chemical Structure ings from inside your textbook because I normally ex- Getting Started pect you to read the entire chapter. 4. Finally, there will often be a Supplement that con- If you’ve downloaded this guide, it means you’re getting tains comments on material that I have found espe- serious about studying. So do you already have an idea cially tricky. Material that I expect you to memorize about how you’re going to study? will also be placed here. Maybe you thought you would read all of chapter 1 and then try the homework? That sounds good. Or maybe you Checklist thought you’d read a little bit, then do some problems from the book, and just keep switching back and forth? That When you have finished studying Chapter 1, you should be sounds really good. Or … maybe you thought you would able to:1 go through the chapter and make a list of all of the impor- tant technical terms in bold? That might be good too. 1. State the number of valence electrons on the following atoms: H, Li, Na, K, Mg, B, Al, C, Si, N, P, O, S, F, So what point am I trying to make here? Simply this – you Cl, Br, I should do whatever you think will work. Try something. Do something. Anything you do will help. 2. Draw and interpret Lewis structures Are some things better to do than others? Of course! But a. Use bond lengths to predict bond orders, and vice figuring out which study methods work well and which versa ones don’t will take time.
    [Show full text]
  • 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°.
    [Show full text]
  • Electron Configurations, Orbital Notation and Quantum Numbers
    5 Electron Configurations, Orbital Notation and Quantum Numbers Electron Configurations, Orbital Notation and Quantum Numbers Understanding Electron Arrangement and Oxidation States Chemical properties depend on the number and arrangement of electrons in an atom. Usually, only the valence or outermost electrons are involved in chemical reactions. The electron cloud is compartmentalized. We model this compartmentalization through the use of electron configurations and orbital notations. The compartmentalization is as follows, energy levels have sublevels which have orbitals within them. We can use an apartment building as an analogy. The atom is the building, the floors of the apartment building are the energy levels, the apartments on a given floor are the orbitals and electrons reside inside the orbitals. There are two governing rules to consider when assigning electron configurations and orbital notations. Along with these rules, you must remember electrons are lazy and they hate each other, they will fill the lowest energy states first AND electrons repel each other since like charges repel. Rule 1: The Pauli Exclusion Principle In 1925, Wolfgang Pauli stated: No two electrons in an atom can have the same set of four quantum numbers. This means no atomic orbital can contain more than TWO electrons and the electrons must be of opposite spin if they are to form a pair within an orbital. Rule 2: Hunds Rule The most stable arrangement of electrons is one with the maximum number of unpaired electrons. It minimizes electron-electron repulsions and stabilizes the atom. Here is an analogy. In large families with several children, it is a luxury for each child to have their own room.
    [Show full text]
  • 1 CHEM 1411 Chapter 5 Homework Answers 1. Which Statement Regarding the Gold Foil Experiment Is False?
    1 CHEM 1411 Chapter 5 Homework Answers 1. Which statement regarding the gold foil experiment is false? (a) It was performed by Rutherford and his research group early in the 20th century. (b) Most of the alpha particles passed through the foil undeflected. (c) The alpha particles were repelled by electrons (d) It suggested the nuclear model of the atom. (e) It suggested that atoms are mostly empty space. 2. Ernest Rutherford's model of the atom did not specifically include the ___. (a) neutron (b) nucleus (c) proton (d) electron (e) electron or the proton 3. The gold foil experiment suggested ___. (a) that electrons have negative charges (b) that protons have charges equal in magnitude but opposite in sign to those of electrons (c) that atoms have a tiny, positively charged, massive center (d) the ratio of the mass of an electron to the charge of an electron (e) the existence of canal rays 4. Which statement is false? (a) Ordinary chemical reactions do not involve changes in nuclei. (b) Atomic nuclei are very dense. (c) Nuclei are positively charged. (d) Electrons contribute only a little to the mass of an atom (e) The nucleus occupies nearly all the volume of an atom. 2 5. In interpreting the results of his "oil drop" experiment in 1909, ___ was able to determine ___. (a) Robert Millikan; the charge on a proton (b) James Chadwick; that neutrons are also present in the nucleus (c) James Chadwick; that the masses of protons and electrons are nearly identical (d) Robert Millikan; the charge on an electron (e) Ernest Rutherford; the extremely dense nature of the nuclei of atoms 6.
    [Show full text]
  • Lecture 3. the Origin of the Atomic Orbital: Where the Electrons Are
    LECTURE 3. THE ORIGIN OF THE ATOMIC ORBITAL: WHERE THE ELECTRONS ARE In one sentence I will tell you the most important idea in this lecture: Wave equation solutions generate atomic orbitals that define the electron distribution around an atom. To start we need to simplify the math by switching to spherical polar coordinates (everything = spherical) rather than Cartesian coordinates (everything = at right angles). So the wave equations generated will now be of the form ψ(r, θ, Φ) = R(r)Y(θ, Φ) where R(r) describes how far out on a radial trajectory from the nucleus you are. r is a little way out and is small Now that we are extended radially on ψ, we need to ask where we are on the sphere carved out by R(r). Think of blowing up a balloon and asking what is going on at the surface of each new R(r). To cover the entire surface at projection R(r), we need two angles θ, Φ that get us around the sphere in a manner similar to knowing the latitude & longitude on the earth. These two angles yield Y(θ, Φ) which is the angular wave function A first solution: generating the 1s orbit So what answers did Schrodinger get for ψ(r, θ, Φ)? It depended on the four quantum numbers that bounded the system n, l, ml and ms. So when n = 1 and = the solution he calculated was: 1/2 -Zr/a0 1/2 R(r) = 2(Z/a0) *e and Y(θ, Φ) = (1/4π) .
    [Show full text]
  • A Computational Study of Ruthenium Metal Vinylidene Complexes: Novel Mechanisms and Catalysis
    A Computational Study of Ruthenium Metal Vinylidene Complexes: Novel Mechanisms and Catalysis David G. Johnson PhD University of York, Department of Chemistry September 2013 Scientist: How much time do we have professor? Professor Frink: Well according to my calculations, the robots won't go berserk for at least 24 hours. (The robots go berserk.) Professor Frink: Oh, I forgot to er, carry the one. - The Simpsons: Itchy and Scratchy land Abstract A theoretical investigation into several reactions is reported, centred around the chemistry, formation, and reactivity of ruthenium vinylidene complexes. The first reaction discussed involves the formation of a vinylidene ligand through non-innocent ligand-mediated alkyne- vinylidene tautomerization (via the LAPS mechanism), where the coordinated acetate group acts as a proton shuttle allowing rapid formation of vinylidene under mild conditions. The reaction of hydroxy-vinylidene complexes is also studied, where formation of a carbonyl complex and free ethene was shown to involve nucleophilic attack of the vinylidene Cα by an acetate ligand, which then fragments to form the coordinated carbonyl ligand. Several mechanisms are compared for this reaction, such as transesterification, and through allenylidene and cationic intermediates. The CO-LAPS mechanism is also examined, where differing reactivity is observed with the LAPS mechanism upon coordination of a carbonyl ligand to the metal centre. The system is investigated in terms of not only the differing outcomes to the LAPS-type mechanism, but also with respect to observed experimental Markovnikov and anti-Markovnikov selectivity, showing a good agreement with experiment. Finally pyridine-alkenylation to form 2-styrylpyridine through a half-sandwich ruthenium complex is also investigated.
    [Show full text]
  • 6. Basic Properties of Atoms
    6. Basic properties of atoms ... We will only discuss several interesting topics in this chapter: Basic properties of atoms—basically, they are really small, really, really, really small • The Thomson Model—a really bad way to model the atom (with some nice E & M) • The Rutherford nuclear atom— he got the nucleus (mostly) right, at least • The Rutherford scattering distribution—Newton gets it right, most of the time • The Rutherford cross section—still in use today • Classical cross sections—yes, you can do this for a bowling ball • Spherical mirror cross section—the disco era revisited, but with science • Cross section for two unlike spheres—bowling meets baseball • Center of mass transformation in classical mechanics, a revised mass, effectively • Center of mass transformation in quantum mechanics—why is QM so strange? • The Bohr model—one wrong answer, one Nobel prize • Transitions in the Bohr model—it does work, I’m not Lyman to you • Deficiencies of the Bohr Model—how did this ever work in the first place? • After this we get back to 3D QM, and it gets real again. Elements of Nuclear Engineering and Radiological Sciences I NERS 311: Slide #1 ... Basic properties of atoms Atoms are small! e.g. 3 Iron (Fe): mass density, ρFe =7.874 g/cm molar mass, MFe = 55.845 g/mol N =6.0221413 1023, Avogadro’s number, the number of atoms/mole A × ∴ the volume occupied by an Fe atom is: MFe 1 45 [g/mol] 1 23 3 = 23 3 =1.178 10− cm NA ρ 6.0221413 10 [1/mol]7.874 [g/cm ] × Fe × The radius is (3V/4π)1/3 =0.1411 nm = 1.411 A˚ in Angstrøm units.
    [Show full text]
  • Atomic Structure
    1 Atomic Structure 1 2 Atomic structure 1-1 Source 1-1 The experimental arrangement for Ruther- ford's measurement of the scattering of α particles by very thin gold foils. The source of the α particles was radioactive radium, a rays encased in a lead block that protects the surroundings from radiation and confines the α particles to a beam. The gold foil used was about 6 × 10-5 cm thick. Most of the α particles passed through the gold leaf with little or no deflection, a. A few were deflected at wide angles, b, and occasionally a particle rebounded from the foil, c, and was Gold detected by a screen or counter placed on leaf Screen the same side of the foil as the source. The concept that molecules consist of atoms bonded together in definite patterns was well established by 1860. shortly thereafter, the recognition that the bonding properties of the elements are periodic led to widespread speculation concerning the internal structure of atoms themselves. The first real break- through in the formulation of atomic structural models followed the discovery, about 1900, that atoms contain electrically charged particles—negative electrons and positive protons. From charge-to-mass ratio measurements J. J. Thomson realized that most of the mass of the atom could be accounted for by the positive (proton) portion. He proposed a jellylike atom with the small, negative electrons imbedded in the relatively large proton mass. But in 1906-1909, a series of experiments directed by Ernest Rutherford, a New Zealand physicist working in Manchester, England, provided an entirely different picture of the atom.
    [Show full text]
  • Rutherford Scattering
    Rutherford Scattering Gavin Cheung F 09328173 November 15, 2010 Abstract A thin piece of gold foil is bombarded with alpha particles using an americium-241 source at several angles. The resulting scattering of the alpha particles is examined by finding the count rate at the angles. It was found that most of the particles were unscattered while a minority were scattered. It is predicted by Rutherford's model that the count rate is proportional to cosec4 of the angle and this relationship was verified. This disproves the plum-pudding model and supports Rutherford's theory. ? Introduction The idea of the atom has been around for millenia yet little could be said about it. By the end of the 19th Century, it became apparent that atoms were a useful tool that could be used to model phenomena in physics and chemistry. J. J. Thomson proposed the plum pudding model in 1904 where the atom is a mass of positive charge with small negatively charged electrons embedded in it like plums in a plum pudding. In 1909, Ernest Rutherford directed the famous experiment where a thin sheet of gold foil was bom- barded with alpha particles. The plum pudding model predicted that the alpha particles would be scattered by the gold atoms by small angles. However, it was found that most of the alpha particles passed straight through the gold foil with little scattering and a very small amount of the alpha particles were scattered by some large angle and some were even backscattered. The only explanation Rutherford had was that the plum pudding model could not be right.
    [Show full text]
  • Rutherford Scattering Simulation
    Name ______________________________ Date______________________ Rutherford Scattering Simulation Ernest Rutherford, (30 August 1871 – 19 October 1937) was a New Zealand-born British physicist and chemist who became known as the father of nuclear physics. He was awarded the noble prize in chemistry in 1908 for his investigations into the disintegration of the elements, and radioactive substances. Rutherford performed his most famous work after he became a Nobel laureate. In 1911, although he could not prove that it was positive or negative, he theorized that atoms have their charge in a very small nucleus and pioneered the Rutherford model of the atom. Through his discovery and interpretation of Rutherford scattering in his gold foil experiment he is widely credited with discovery of the the proton. Rutherford remains the only science Nobel Prize winner to have performed his most famous work after receiving the prize. The popular theory of atomic structure at the time of Rutherford's experiment was the "plum pudding model". This model was developed in 1904 by J. J. Thomson, the scientist who discovered the electron. This theory held that the negatively charged electrons in an atom were floating (sometimes moving) in a sea of positive charge. The gold foil experiment fires a series of positively charged alpha particles (helium nuclei) at a very thin sheet of gold foil. If Thomson's Plum Pudding model was to be accurate, the big alpha particles should have passed through the gold foil with only a few minor deflections. This is because the alpha particles are larger and heavier than electrons GOLD FOIL EXPERIMENT Expected results: alpha particles passing through the plum pudding model of the atom undisturbed.
    [Show full text]
  • Coercing Magnetism Into Diamagnetic Ceramics: a Case Study in Alumina Erik Nykwest University of Connecticut - Storrs, [email protected]
    University of Connecticut Masthead Logo OpenCommons@UConn Doctoral Dissertations University of Connecticut Graduate School 4-25-2019 Coercing Magnetism into Diamagnetic Ceramics: A Case Study in Alumina Erik Nykwest University of Connecticut - Storrs, [email protected] Follow this and additional works at: https://opencommons.uconn.edu/dissertations Recommended Citation Nykwest, Erik, "Coercing Magnetism into Diamagnetic Ceramics: A Case Study in Alumina" (2019). Doctoral Dissertations. 2136. https://opencommons.uconn.edu/dissertations/2136 Coercing Magnetism into Diamagnetic Ceramics: A Case Study in Alumina Erik Carl Nykwest, Ph.D. University of Connecticut, 2019 Ceramics are very diverse class of materials whose properties can vary greatly. It is this diversity that make ceramics so useful in advanced technology. The relatively open crystal structure of ceramics makes it pos- sible to impart functionalities via judicious doping. This work focuses on developing a generalized method for introducing magnetism into normally non-magnetic (diamagnetic) ceramics, using the example case of alumina (Al2O3).Here, substitutional doping of Al atoms with 3d transition metal in α- and θ-alumina was studied. Density functional theory was used to predict the structural, electronic, and magnetic properties of doped alumina, as well as its stability. The results show that adding small concentrations of transition metals to alumina may increase magnetic activity by generating unpaired electrons whose net magnetic moments may couple with external magnetic fields. The dopant species and dopant coordination environment are the most important factors in determining the spin density distribution (localized or delocalized from the dopant atom) and net magnetic moment, which strongly direct the ability of the doped alumina to couple with an ex- ternal field.
    [Show full text]