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Unit 1: Matter & Energy • Description • Measurement • SI - Metric System CHEM 1411, revised 10 Aug 2007 • Conversions • Thermodynamics Definition - Matter • Anything the has mass and can be detected and measured, made up of atoms and may be a solid, a liquid, gaseous or a plasma The The Nature Nature of of Matter Matter Gold Mercury Chemists are interested in the nature of matter and how this is related to its atoms and molecules. • An atom is the smallest particle of an element that has the chemical properties of the element. Copper atoms on silica surface. Distance across = 1.8 nanometer (1.8 x 10-9 m) Chemistry & Matter • We can explore the MACROSCOPIC world — what we can see — • to understand the PARTICULATE worlds we cannot see. • We write SYMBOLS to describe these worlds. Conservation • Conservation of Matter - matter is neither created nor destroyed must account for all matter during a reaction • Conservation of Energy - energy is neither created nor destroyed, changed from one form to another must account for all energy • SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement. – Reasonably well understood. • LIQUIDS — have no fixed shape and may not fill a container completely. – Not well understood. • GASES — expand to fill their container. Good theoretical understanding. Fig. 1.2, p.13 Fig. 1.1, p.12 Matter Classification Element • Pure substance that cannot be decomposed any further by ordinary means • About 115 elements listed on Periodic Table metals, non-metals, metalloids, atomic number, atomic symbol Element - definition • An element is a type of matter composed of atoms that all have exactly the same positive charge on their nuclei. In other words, all atoms of an element have the same atomic number . http://antoine.frostburg.edu/chem/senese/101/matter/faq/what-is-an-element.shtml Periodic Table • Dmitri Mendeleev developed the modern periodic table. Argued that element properties are periodic functions of their atomic weights. • We now know that element properties are periodic functions of their ATOMIC NUMBERS. Short Form of Periodic Table Long Form-Periodic Table p.79a p.79b Regions of the Periodic Table Group 1A: Alkali Metals Li, Na, K, Rb, Cs Cutting sodium metal Group 2A: Alkaline Earth Metals Be, Mg, Ca, Sr, Ba, Ra Magnesium Magnesium oxide Group 7A: Halogens F, Cl, Br, I, At Group 8A: Noble Gases He, Ne, Ar, Kr, Xe, Rn Group 6A: O, S, Se, Te, Po Sulfuric acid dripping from snot-tite in cave in Mexico Elemental S has a ring structure. Transition Elements Lanthanides and actinides Iron in air gives iron(III) oxide Forms of the Elements • Most are monoatomic – a single atom is the element, examples: Zn (s), Al (s), Cs (s) • Some are Diatomic – two atoms bound together form the element (not single atom shown of Periodic Table) H2 (g); N2 (g); O2 (g); F2 (g); Cl2 (g); Br2 (l); I2 (s); Compound • Pure substance composed of two or more elements bonded together in a definite ratio by weight. Identified by a unique set of physical and chemical properties. H2O and H2O2 Na2CrO4 and Na2Cr2O7 Compound - definition • Water – H2O 2 atoms of hydrogen bound to 1 atom of oxygen • Hydrogen Peroxide – H2O2 2 atoms of hydrogen bound to 2 atoms of oxygen ALL water molecules are 11.19 % H by weight and 88.81% oxygen by weight • H2O2 5.93% H by weight and 94.07 % oxygen by weight Comparison of Physical Properties Water and Hydrogen Peroxide Water Hydrogen peroxide Melting point °C 0.0 -2 Boiling point °C 100 158 Density, g/mL 1.0 1.46 Compounds • Same three component elements – Na, Cr, O but different weight ratios Na2CrO4 Na2Cr2O7 Terms for Matter • • • • • • Heterogeneous Homogeneous Mixture Solution Physical process Chemical process • • • • • • Element Compound Atom Solid Liquid Gas Classification of Energy Description of Energy Energy Potential Kinetic (position or stored) (motion) Potential Potential & & Kinetic Kinetic Energy Energy Potential energy — energy a motionless body has by virtue of its position. Potential Potential & & Kinetic Kinetic Energy Energy Kinetic energy — energy of motion • Translation Potential Energy on the Atomic Scale • Positive and negative particles (ions) attract one another. • Two atoms can bond • As the particles attract they have a lower potential energy NaCl — composed of Na+ and Cl- ions. Potential Energy Potential energy is stored energy and the energy of position––There are several forms of potential energy. Chemical Energy is energy stored in the bonds of atoms and molecules. It is the energy that holds these particles together. Biomass, petroleum, natural gas, and propane are examples of stored chemical energy. Stored Mechanical Energy is energy stored in objects by the application of a force. Compressed springs and stretched rubber bands are examples of stored mechanical energy. Nuclear Energy is energy stored in the nucleus of an atom––the energy that holds the nucleus together. The energy can be released when the nuclei are combined or split apart. Nuclear power plants split the nuclei of uranium atoms in a process called fission. The sun combines the nuclei of hydrogen atoms in a process called fusion. Scientists are working on creating fusion energy on earth, so that someday there might be fusion power plants. Gravitational Energy is the energy of position or place. A rock resting at the top of a hill contains gravitational potential energy. Hydropower, such as water in a reservoir behind a dam, is an example of gravitational potential energy. Kinetic energy — energy of motion. rotate vibrate translate Kinetic Energy Kinetic energy is motion––of waves, electrons, atoms, molecules, substances, and objects. Electrical Energy is the movement of electrical charges. Everything is made of tiny particles called atoms. Atoms are made of even smaller particles called electrons, protons, and neutrons. Applying a force can make some of the electrons move. Electrical charges moving through a wire is called electricity. Lightning is another example of electrical energy. Radiant Energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays and radio waves. Light is one type of radiant energy. Solar energy is an example of radiant energy. Thermal Energy, or heat, is the internal energy in substances––the vibration and movement of the atoms and molecules within substances. Geothermal energy is an example of thermal energy. Motion Energy is the movement of objects and substances from one place to another. Objects and substances move when a force is applied according to Newton’s Laws of Motion. Wind is an example of motion energy. Sound is the movement of energy through substances in longitudinal (compression/rarefaction) waves. Sound is produced when a force causes an object or substance to vibrate––the energy is transferred through the substance in a wave. ENERGY is the capacity to do work or transfer heat. HEAT is the form of energy that flows between 2 objects because of their difference in temperature. Other forms of energy — •light •electrical •kinetic and potential Forms of Energy Energy Heat Light Electricity Definitions • Heat – a measure of the amount of energy transferred from one body to another because of the temperature difference between those bodies Definition • Electromagnetic Radiation (light) – interacting electric and magnetic waves that propagate through a vacuum at 3 X 108 m/s, includes gamma rays, ultraviolet , visible light, infrared, radio waves Planck’s Equation • E = hc λ h is a constant value c is the speed of light in a vacuum λ is the wavelength of electromagnetic radiation Definition • Electrical Energy – energy of charges ( + or - ) as a result of position or motion Dissimilar charges attract Similar charges repel Thermodynamics • Thermodynamics is the science of heat (energy) transfer. • Heat transfers until thermal equilibrium is established. Terms for Energy • • • • • Kinetic Energy Potential Energy Heat Light Thermodynamics • • • • Plank’s Equation Electrical Energy Wavelength Thermal Equilibrium