DOCSLIB.ORG

15.6 News & Views MH

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
15.6 News & Views MH NATURE|Vol 441|15 June 2006 NEWS & VIEWS by Daw et al.1, exploring these questions 1. Daw, N. D. et al. Nature 441, 876–879 (2006). ambient conditions, preventing further study will require interdisciplinary approaches, in 2. Lee, D. Curr. Opin. Neurobiol. 16, 191–198 (2006). of its physical properties. During decompres- 3. Sutton, R. S. & Barto, A. G. Reinforcement Learning: An which the computational theories inspire Introduction (MIT Press, Cambridge, MA, 1998). sion from the conditions under which it is and guide behavioural and neurobiological 4. Ramnani, N. & Owen, A. M. Nature Rev. Neurosci. 5, formed, the glass transforms back to an amor- ■ experiments. 184–194 (2004). phous version of molecular solid CO2. Devel- Daeyeol Lee is in the Department of Brain and 5. Schweighofer, N. & Doya, K. Neural Netw. 16, 5–9 (2003). oping carbonia glasses that can be recovered to Cognitive Sciences, University of Rochester, 6. Soltani, A., Lee, D. & Wang, X.-J. Neural Netw. (in the press). 7. Doya, K. Neural Netw. 15, 495–506 (2002). ambient conditions will be one of the first Rochester, New York 14627, USA. 8. Aston-Jones, G. & Cohen, J. D. Annu. Rev. Neurosci. 28, challenges for future research. e-mail: [email protected] 403–450 (2005). These results1 have implications for liquid- state physics, and inform us about the condi- tions under which CO2 undergoes various phase transitions, including melting7. There SOLID-STATE CHEMISTRY has been much discussion of the newly recog- nized phenomenon of polyamorphism — the ability of a material to exist in several different A glass of carbon dioxide amorphous forms — and of phase transitions Paul F. McMillan between distinct liquid states of a single sub- stance. These are driven by density or entropy Carbon is unusual in its family of elements because it has gaseous oxides. changes between glassy or liquid forms at con- 8 But under high pressure, carbon dioxide forms crystalline solids and can stant chemical composition . It has been sug- gested that such transitions occur for many become a glass — so revealing the chemical family resemblance. liquids and glasses, including water, silica and germania. The observation by Santoro et al.1 Everyone is familiar with the common forms tion to 80 GPa at ambient temperature3. that, upon decompression, glassy carbonia of silicon dioxide (SiO2, silica), such as the Recently, however, experiments showed that transforms from a dense amorphous solid crystalline version known as quartz, the major under simultaneous high-pressure and high- containing networks of single bonds, to an component of sand. When melted and cooled temperature conditions, CO2 molecules amorphous solid containing molecular CO2, rapidly, and usually mixed with metal oxides, undergo bond-breaking and re-formation reac- represents a dramatic example of polyamor- sand forms silica-based glasses that we use to tions, producing a three-dimensional network phic behaviour, analogous to that observed for 9,10 make many useful things, ranging from win- of polymerized tetrahedral CO4 units. This net- amorphous silicon or liquid phosphorus . It dows to champagne bottles. A glassy dioxide work is analogous to the crystalline silica struc- follows that anomalies are to be expected in of germanium (GeO2, germania) is also tures found in minerals such as cristobalite, the melting behaviour of crystalline CO2 known, and is added to the kilometre-long tridymite or quartz4,5, although it reverts to solids, or that a phase transition may occur in silica glassy fibres used in optical telecommu- solids containing CO2 molecules at pressures the liquid state at high pressure, between the nications, to control their refractive index. below 1 GPa. Other nitrogen- and oxygen-con- molecular and the polymeric forms. Carbon belongs to the same family of elements taining molecules also undergo solid-state The discovery of mineral-like polymeric as silicon and germanium, but carbon dioxide chemistry at high pressure6. These results have and ionic solids that form at high pressure, (CO2, carbonia) glass has remained a theoret- generated great excitement among chemists. based on the light elements carbon, oxygen ical possibility. On page 857 of this issue, The newly prepared materials might have and nitrogen, opens up a new area in solid- however, Santoro and colleagues1 show that useful properties for technological applications. state chemistry. Carbonia-based minerals and carbonia glass can be made when a high- Studies on the polymeric, silica-like form of glasses could give rise to useful technological density form of solid CO2 is melted and cooled CO2 suggest that it is ‘super-hard’ and that it is materials, if we can recover them to ambient under high-pressure conditions. an optically nonlinear material — for example, conditions. These findings will also help set Carbon, silicon and germanium are the first it causes doubling of the frequency of light from the rules for understanding structure, bonding three members of group IV of the periodic a laser4,5. The discovery also has implications for and thermodynamic properties as we move table, which also includes the heavier elements geochemistry, because the conditions found in our experiments into the high-pressure, high- tin and lead. These last two elements form both Earth’s mantle could induce the formation of temperature conditions mimicking those deep monoxides and dioxides, which have been used these newly discovered forms of carbon oxides. inside planetary interiors. ■ 2 as pigments since ancient times . In contrast, Incorporation of CO2 into solid-state com- Paul F. McMillan is in the Department of only the dioxides of silicon and germanium pounds formed under high temperature and Chemistry, Christopher Ingold Laboratory and occur as stable solids. Once we reach carbon, pressure may even lead to methods for disposal Materials Chemistry Centre, University College the lightest member of the series, we find that of this environmentally problematic gas. London, 20 Gordon Street, London WC1H 0AJ, both carbon monoxide and carbon dioxide are So, a crystalline silica-like form of CO2 has UK, and in the Davy–Faraday Laboratory, Royal stable molecules, but these exist as gases at been made, but how about a glassy version? Institution of Great Britain, London. ambient temperature and pressure. As we rise Enter Santoro and colleagues1, who have pre- e-mail: [email protected] up a group of the periodic table, such anom- pared a dense, polymeric amorphous form of alous jumps in the properties of compounds this compound that is analogous to silica- and 1. Santoro, M. et al. Nature 441, 857–860 (2006). 2. Ball, P. Bright Earth: The Invention of Colour (Viking, London, formed from the elements of that group often germania-based glasses. They did this by com- 2001). occur. Smooth changes in chemical and physi- pressing molecular solid CO2 to pressures of 3. Liu, L.-G. & Bassett, W. A. Elements, Oxides, Silicates: High- cal properties are generally observed among the 40–65 GPa with heating, then cooling it to Pressure Phases with Implications for the Earth's Interior heavier members of the group, but the lightest ambient temperature. Their result is at least as (Oxford Univ. Press, 1986). 4. Iota, V. et al. Science 283, 1510–1513 (1999). element behaves quite differently. exciting as the discovery of the polymeric crys- 5. Yoo, C.-S. et al. Phys. Rev. Lett. 83, 5527–5530 (1999). Carbon dioxide is a linear molecule with talline carbon dioxide solid, and the chemistry 6. Eremets, M. I. et al. J. Chem. Phys. 121, 11296–11300 (2004). strong carbon–oxygen double bonds. Freezing of carbonia-based glasses is now open for 7. Tschauner, O. et al. J. Phys. Rev. Lett. 87, 075701 (2001). or high-pressure treatment condenses this exploration. 8. McMillan, P. F. J. Mat. Chem. 14, 1506–1512 (2004). 9. Katayama, Y. et al. Nature 403, 170–173 (2000). gas into solid forms, in which the molecules So far, glassy carbonia is like its crystalline 10. McMillan, P. F., Wilson, M., Daisenberger, D. & Machon, D. remain intact, even under extreme pressuriza- equivalent in that it is not yet recoverable to Nature Mater. 4, 680–684 (2005). 823 © 2006 Nature Publishing Group.
Load more

Recommended publications
  • Review Polyamorphism in Water
    No. 3] Proc. Jpn. Acad., Ser. B 86 (2010) 165 Review Polyamorphism in water By Osamu MISHIMAÃ1,† (Communicated by Hiroo INOKUCHI, M.J.A.) Abstract: Water, the most common and important liquid, has peculiar properties like the density maximum at 4 C. Such properties are thought to stem from complex changes in the bond- ing-network structure of water molecules. And yet we cannot understand water. The discovery of the high-density amorphous ice (HDA) in 1984 and the discovery of the apparently discontinuous change in volume of amorphous ice in 1985 indicated experimentally clearly the existence of two kinds of disordered structure (polyamorphism) in a one-component condensed-matter system. This fact has changed our viewpoint concerning water and provided a basis for a new explanation; when cooled under pressure, water would separate into two liquids. The peculiar properties of water would be explained by the existence of the separation point: the liquid-liquid critical point (LLCP). Presently, accumulating evidences support this hypothesis. Here, I describe the process of my experimental studies from the discovery of HDA to the search for LLCP together with my thoughts which induced these experiments. Keywords: Polyamorphism, water, amorphous ice, liquid-liquid transition, liquid-liquid critical point, liquid and glass lizes easily between 150 K and 235 K (Fig. 2). 1. Introduction The temperature domain of the easy crystallization In the 17th century, Galileo thought ice should was named ‘‘no-man’s land’’ (NML). Consequently, be rareed water. This stimulated the experimental- measurement of the liquid water in this NML is tech- ists of ‘‘Academie del Cimento’’.
    [Show full text]
  • Microgravity Studies of Liquid-Liquid Phase Transitions in Alumina-Yttria Melts
    FINAL REPORT January 31,2004 MICROGRAVITY STUDIES OF LIQUID-LIQUID PHASE TRANSITIONS IN ALUMINA-YTTRIA MELTS Flight Definition, Materials Science Subdiscipline: Ceramics and Glasses NASA Contract Number NAS8-98092 April 1998 to January 2004 Principal Investigator: Dr. Richard Weber Co-Investigator: Dr. Paul Nordine Containerless Research, Inc. Evanston, IL 6020 1-3 149 Phone: 8471467-2678, Fax 8471467-2679 email: [email protected] COTR: Buddy Guynes George C. Marshall Space Flight Center Marshall Space Flight Center, AL 35812 Proiect Summary: The scientific objective of this research is to increase the fundamental knowledge base for liquid- phase processing of technologically important oxide materials. The experimental objective is to define conditions and hardware requirements for microgravity flight experiments to test and expand the experimental hypotheses that: 1. Liquid phase transitions can occur in undercooled melts by a diffusionless process. 2. Onset of the liquid phase transition is accompanied by a large change in the temperature dependence of melt viscosity. Experiments on undercooled YAG (Y3A15012)- and rare earth oxide aluminate composition liquids demonstrated a large departure from an Arrhenian temperature dependence of viscosity. Liquid YAG is nearly inviscid at its 2240 K melting point. Glass fibers were pulled from melts undercooled by ca. 600 K indicating that the viscosity is on the order of 100 Pans (1000 Poise) at 1600 K. This value of viscosity is 500 times greater than that obtained by extrapolation of data for temperatures above the melting point of YAG. These results show that the liquids are extremely fragile and that the onset of the highly non-Arrhenian viscosity-temperature relationship occurs at a temperature considerably below the equilibrium melting point of the solid phases.
    [Show full text]
  • Liquid Polyamorphism: Possible Relation to the Anomalous Behaviour of Water
    Eur. Phys. J. Special Topics 161, 1–17 (2008) c EDP Sciences, Springer-Verlag 2008 THE EUROPEAN DOI: 10.1140/epjst/e2008-00746-3 PHYSICAL JOURNAL SPECIAL TOPICS Liquid polyamorphism: Possible relation to the anomalous behaviour of water H.E. Stanley1,a, P. Kumar1, G. Franzese2,L.Xu1,Z.Yan1,M.G.Mazza1, S.V. Buldyrev13, S.-H. Chen4, and F. Mallamace5 1 Center for Polymer Studies and Dept. of Physics, Boston University, Boston, MA 02215, USA 2 Departament de F´ısica Fonamental, Univ. de Barcelona, Diagonal 647, Barcelona 08028, Spain 3 Department of Physics, Yeshiva University, 500 West 185th Street, New York, NY 10033, USA 4 Nuclear Science and Engineering Dept., Mass. Inst. of Technology, Cambridge, MA 02139, USA 5 Dipartimento di Fisica, Univ. Messina, Vill. S. Agata, CP 55, 98166 Messina, Italy Abstract. We present evidence from experiments and computer simulations supporting the hypothesis that water displays polyamorphism, i.e., water sepa- rates into two distinct liquid phases. This concept of a new liquid-liquid phase transition is finding application to other liquids as well as water, such as silicon and silica. Specifically, we investigate, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid-liquid critical point in (i) Two models of water, TIP5P and ST2, which display a first order liquid-liquid phase transition at low temperatures; (ii) the Jagla model, a spherically symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions; and (iii) A Hamiltonian model of water where the idea of two length/energy scales is built in.
    [Show full text]
  • Pressure-Induced Amorphization and Polyamorphism in One-Dimensional Single Crystal Tio2 Nanomaterials
    Pressure-induced amorphization and polyamorphism in one-dimensional single crystal TiO2 nanomaterials * Quanjun Li, Bingbing Liu, Lin Wang, Dongmei Li, Ran Liu, Bo Zou, Tian Cui, Guangtian Zou State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China Yue Meng, Ho-kwang Mao HPCAT, Carnegie Institution of Washington, Building 434E, 9700 South Cass Avenue, Argonne, Illinois 60439, USA Zhenxian Liu U2A beamline, Carnegie Institution of Washington, Upton, NY 11973, USA Jing Liu Institute of High Energy Physics, Chinese Academe of Sciences, Beijing 10023, China Jixue Li State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130012, China * Corresponding author. E-mail: [email protected]. Tel/Fax: 86-431-85168256. 1 ABSTRACT: The structural phase transitions of single crystal TiO2-B nanoribbons were investigated in-situ at high-pressure using the synchrotron X-ray diffraction and the Raman scattering. Our results have shown a pressure-induced amorphization (PIA) occurred in TiO2-B nanoribbons upon compression, resulting in a high density amorphous (HDA) form related to the baddeleyite structure. Upon decompression, the HDA form transforms to a low density amorphous (LDA) form while the samples still maintain their pristine nanoribbon shape. HRTEM imaging reveals that the LDA phase has an α- PbO2 structure with short range order. We propose a homogeneous nucleation mechanism to explain the pressure-induced amorphous phase transitions in the TiO2-B nanoribbons. Our study demonstrates for the first time that PIA and polyamorphism occurred in the one-dimensional (1D) TiO2 nanomaterials and provides a new method for preparing 1D amorphous nanomaterials from crystalline nanomaterials.
    [Show full text]
  • Chapter 16 Liquid and Solids
    Homework #2 Chapter 16 Liquid and Solids 7. Vapor Pressure: The pressure exerted by the vapor of a liquid when the vapor and the liquid are in dynamic equilibrium. The vapor pressure reflects the fact that within a system there is a distribution of energies that molecules can have, therefore, some molecules will have enough energy to overcome the intermolecular forces and enter into the gas phase. All liquids have some vapor pressure. The stronger the intermolecular forces the smaller the vapor pressure. All solids also have a vapor pressure. This is why if you leave ice in the freezer for a long time it “disappears.” The vapor pressure of solids is less than the vapor pressure of liquids. As the temperature increases the molecules have more energy, therefore, more molecules can escape into the gas phase (vapor pressure increases). When the vapor pressure is equal to the atmospheric pressure the solution boils. 9. a) Surface Tension As the intermolecular forces increase (↑), surface tension increases (↑). b) Viscosity As the intermolecular forces increase (↑), the viscosity increases (↑). c) Melting Point As the intermolecular forces increase (↑), the melting point increases (↑). d) Boiling Point As the intermolecular forces increase (↑), the boiling point increases (↑). e) Vapor Pressure As the intermolecular forces increase (↑), the vapor pressure decreases (↓). 11. Intermolecular Forces: The forces of attraction/repulsion between molecules. Intramolecular Forces: The forces of attraction/repulsion within a molecule. Intramolecular forces are stronger the intermolecular forces. Types of intermolecular forces: Dipole-Dipole Forces: The interaction between two electric dipoles in different molecules. Hydrogen Bonding: The attraction between a hydrogen atom (that is bonded to an O, N, or F atom) and an O, N, or F atom in a neighboring molecule.
    [Show full text]
  • Thermodynamics of Fluid Polyamorphism
    SUPPLEMENTAL MATERIAL Thermodynamics of Fluid Polyamorphism Mikhail A. Anisimov1,2*, Michal Duška1, 3, Frédéric Caupin4, Lauren E. Amrhein1, Amanda Rosenbaum1, and Richard J. Sadus5 1Department of Chemical & Biomolecular Engineering and Institute for Physical Science & Technology, University of Maryland, College Park, U.S.A. 2Oil and Gas Research Institute of the Russian Academy of Sciences, Moscow, 117333, Russia 3Institute of Thermomechanics, Academy of Sciences of the Czech Republic, 182 00 Prague 8, Czech Republic 4Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumiè re Matiè re, F-69622 Villeurbanne, France 5 Computational Science Laboratory, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia *To whom correspondence should be addressed. Email: [email protected]. 1. Lattice-gas model The lattice-gas model was first introduced by Frenkel in 1932 [1]. In 1952 Yang and Lee [2] showed that the lattice-gas model, which is the simplest model for the vapor-liquid transition, is mathematically equivalent to the Ising model that describes a phase transition between paramagnetic and anisotropic ferromagnetic or antiferromagnetic states. The Ising/lattice-gas model is also used to describe solid-solid phase separation or order-disorder transitions in binary alloys as well as liquid-liquid phase separation in binary fluids. The model plays a special role in the physics of condensed matter because it can be applied to very different systems and phenomena, thereby bridging the gap between the physics of fluids and solid-state physics [3-5]. The volume of the system is divided into cells of molecular size lo . These cells are arranged in a lattice with the coordination number z (z = 6 for a simple cubic lattice).
    [Show full text]
  • Pressure-Induced Amorphization and Existence of Molecular And
    Pressure-induced amorphization and existence of molecular and polymeric amorphous forms in dense SO2 Huichao Zhanga,b, Ondrej Toth´ c, Xiao-Di Liua,1 , Roberto Binid,e , Eugene Gregoryanza,f,g,h, Philip Dalladay-Simpsonh, Simone De Panfilisi , Mario Santoroa,e,j,1, Federico Aiace Gorellia,e,j,1, and Roman Martonˇ ak´ c,1 aKey Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China; bUniversity of Science and Technology of China, Hefei 230026, China; cDepartment of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava, Slovakia; dDepartment of Chemistry, University of Florence, 50121 Florence, Italy; eEuropean Laboratory for Non-Linear Spectroscopy, 50019 Sesto Fiorentino, Italy; fSchool of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom; gCentre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom; hCenter for High Pressure Science Technology Advanced Research, Shanghai, 201203, China; iCentre for Life Nano Science, Istituto Italiano di Tecnologia, 00161 Rome, Italy; and jIstituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (CNR-INO), 50125 Florence, Italy Edited by Michael L. Klein, Temple University, Philadelphia, PA, and approved March 5, 2020 (received for review October 15, 2019) We report here the pressure-induced amorphization and re- pressure induces changes in simple molecular systems include versible structural transformation between two amorphous forms amorphous S (13) and liquid S (14) (for more examples and of SO2: molecular amorphous and polymeric amorphous, with review, see refs. 3 and 4). Dramatic structural changes lead- the transition found at 26 GPa over a broad temperature regime, ing to amorphization have been observed upon compression of 77 K to 300 K.
    [Show full text]
  • The Water Polymorphism and the Liquid–Liquid Transition from Transport Data
    Article The Water Polymorphism and the Liquid–Liquid Transition from Transport Data Francesco Mallamace 1,2,* , Domenico Mallamace 3 , Giuseppe Mensitieri 4 , Sow-Hsin Chen 1 , Paola Lanzafame 3 and Georgia Papanikolaou 3 1 Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; [email protected] 2 CNR ISC, UOS Roma Sapienza, Physics Department, Sapienza University of Rome, 00185 Roma, Italy 3 Departments of ChiBioFarAm Section of Industrial Chemistry, University of Messina, CASPE-INSTM, V.le F. Stagno d’Alcontres 31, 98166 Messina, Italy; [email protected] (D.M.); [email protected] (P.L.); [email protected] (G.P.) 4 Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, P.le Tecchio 80, 80125 Napoli, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-340-233-5213 Abstract: NMR spectroscopic literature data are used, in a wide temperature-pressure range (180–350 K and 0.1–400 MPa), to study the water polymorphism and the validity of the liquid–liquid transition (LLT) hypothesis. We have considered the self-diffusion coefficient DS and the reorientational correlation time tq (obtained from spin-lattice T1 relaxation times), measured, respectively, in bulk and emulsion liquid water from the stable to well inside the metastable supercooled region. As an effect of the hydrogen bond (HB) networking, the isobars of both these transport functions evolve with T by changing by several orders of magnitude, whereas their pressure dependence Citation: Mallamace, F.; Mallamace, become more and more pronounced at lower temperatures. Both these transport functions were D.; Mensitieri, G.; Chen, S.-H.; Lanzafame, P.; Papanikolaou, G.
    [Show full text]
  • Activation Energy Spectrum for Relaxation and Polyamorphism in An
    Activation energy spectrum for relaxation and polyamorphism in an ultra-viscous metallic glass former Isabella Gallino1,*, Daniele Cangialosi2, Zach Evenson3, Lisa Schmitt1,4, Simon Hechler1,5, Moritz Stolpe1, and Beatrice Ruta5,6 1 Chair of Metallic Materials, Saarland University, Campus C6.3, 66123 Saarbrücken, Germany 2 Materials Physics Center (CFM/MPC), Paseo Lardizabal 5, 20018 San Sebastian, Spain 3 Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department, Technische Universität München, Lichtenbergstrasse 1, 85748 Garching, Germany 4 fem Research Institute for Precious Metals & Metals Chemistry, Katharinenstrasse 17, 73525 Schwäbisch Gmünd, Germany 5 ESRF—The European Synchrotron, CS40220, 38043 Grenoble, France 6 Institute of Light and Matter, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex, France. *corresponding author: Isabella Gallino. E-mail address: [email protected]. Tel: +49 (0)681 302 2052 Abstract: Many glass-formers exhibit phase transitions between two distinct liquid states. For some metallic glass-formers, the liquid-liquid transition is experimentally found in the supercooled liquid at intermediate temperature between the melting point and the glass transition temperature Tg. We report here on a liquid-liquid transition in an ultra-viscous metallic glass-former, accessed during long-time annealing. This study is conducted on the Au49Cu26.9Si16.3Ag5.5Pd2.3 composition with a liquid-liquid transition temperature slightly lower than Tg. The consequence is that the high-temperature kinetically fragile liquid freezes into the glass during conventional processing and the underlying liquid-liquid transition is thus accessed by the system during annealing below Tg. Upon reheating, the reverse transformation is observed by calorimetry.
    [Show full text]
  • Agenda Jan 21, 2020 Return Notes Pages - a Couple of Things I Noticed
    Agenda Jan 21, 2020 Return Notes pages - a couple of things I noticed Quick Check using your 13.3 notes Return notes - and I noticed a couple of areas I need to give you some additional insights. Kinetic Molecular Theory (for gases) The kinetic molecular theory is able to explain the behavior of most gases using the ideas that gas particles are very small, very far apart, moving quickly, colliding with each other and the walls of a container and that the higher the temperature the faster the particles are moving and the greater their average kinetic energy. In liquids the particles are still moving, but there are significant attractions in between molecules that hold them closer together in the flowing liquid phase. (intermolecular attractions) Intermolecular forces in liquids can result in properties like Viscosity - which is a measure of the resistance of a liquid to flow. It is determined by the type and strength of intermolecular forces in the liquid, the shape of the particles and temperature. As temperature increases the particles can flow more easily as they move more quickly, so the viscosity of the liquid decreases. Intermolecular forces in liquids can result in properties like Viscosity - which is a measure of the resistance of a liquid to flow. It is determined by the type and strength of intermolecular forces in the liquid, the shape of the particles and temperature. As temperature decreases the particles slow down and so the resistance to flow increases, in other words the viscosity increases. Intermolecular forces in liquids can result in properties like Surface tension and capillary action - which we will observe more closely after the Quick Check questions.
    [Show full text]
  • 13 Intermolecular Forces, Liquids, and Solids
    13Intermolecular Forces, Liquids, and Solids The four types of solids Intermolecular Forces of Attraction • Ch 12 was all about gases… particles that don’t attract each other. Intermolecular Forces of Attraction • Ch 13 is about liquids and solids… where the attraction between particles allows the formation of solids and liquids. Intermolecular Forces of Attraction • These attractions are called “intermolcular forces of attractions” or IMF’s for short. • Intermolcular forces vs intramolecular forces Four Solids – Overview • Molecular Solids (particles with IMF’s) • Metals (metallic bonding) • Ionic Solids (ionic bonding) • Covalent Network Solids (covalent bonding) Molecular Solids • Molecules or noble gases (individual particles) Molecular Solid Examples • H O 2 • C2H5OH • CO2 • C6H12O6 • CH 4 • The alkanes, alkenes, etc. • NH 3 • The diatomic molecules • NO 2 • The noble gases • CO • C2H6 Metals • A lattice of positive ions in a “sea of electrons” • Metal atoms have low electronegativity Metal Examples • Pb • Brass (Cu + Zn) • Ag • Bronze (Cu + Sn) • Au • Stainless Steel (Fe/Cr/C) • Cu • Zn • Fe Ionic Solids • A lattice of positive and negative ions Ionic Solid Examples • NaCl • CaCl2 • KCl • MgSO4 • KI • Fe2O3 • FeCl3 • AgNO3 • CaCO3 • + ion & - ion Covalent Network Solids • Crystal held together with covalent bonds Covalent Network Solid Examples • C(diamond) • C(graphite) • SiO2 (quartz, sand, glass) • SiC • Si • WC • BN Properties of Metals Metals are good conductors of heat and electricity. They are shiny and lustrous. Metals can be pounded into thin sheets (malleable) and drawn into wires (ductile). Metals do not hold onto their valence electrons very well. They have low electronegativity. Properties of Ionic Solids • Brittle • High MP & BP • Dissolves in H2O • Conducts as (l), (aq), (g) Electrical Conductivity Intermolecular Forces (IMFs) • Each intermolecular force involves + and – attractions.
    [Show full text]
  • Molecules to Materials 1
    SERIES I ARTICLE Molecules to Materials 1. An Overview of Functional Molecular Solids T P Radhakrishnan With the advent of modern physics and chemistry, T P Radhakrishnan is in the School of Chemistry, fundamentally new types of materials have been created in Central University of this century. Various types of forces operating in different Hyderabad, classes of solids are exploited in the design of molecular Hyderabad 500 046. materials. A variety of fabrication techniques have been developed to make materials with the desired properties. An overview of these aspects is provided in this article. Historical Perspective The kinds of materials that have been developed and used over the course of history serve as excellent indicators of the evolution of technology, and civilisation at large. For instance, the early growth of civilisation has been described in terms of the stone, copper, bronze and iron ages. The earliest materials were those which were readily available in nature, like stone, clay and wood and the technology consisted' in reshaping and restructuring physically these materials to suit specific purposes such as weaponry and utensils. The most intricate process at this stage perhaps involved the fabrication of ceramics such as porcelain by baking clays, a practice that Discovery of dates back to the eighth millennium Be. Discovery of procedures for procedures for extraction of metals from their ores and extraction of fabrication of alloys was a major revolution in the history of metals from their materials. Here was a case of complete transformation of the ores and physical and chemical properties of a material. Equally fabrication of alloys fantastic was the discovery of glass-making, a process in was a major which the optical properties of the starting substance, sand, revolution in the are completely and drastically modified.
    [Show full text]