Chemistry<br />Definition – study of the composition and properties of matter and the energy transformations accompanying changes in the structure of matter<br />
Major Branches of Chemistry<br /><ul><li>Inorganic Chemistry – Study of all the elements other than Carbon
Organic Chemistry – Study of compounds containing carbon
Biochemistry – study of chemical processes in living things
NuclearChemistry – study of radioactivity, the nucleus and the changes that the nucleus undergoes</li></li></ul><li> Democritus<br /> Aristotle<br />Early Greek Theories<br /><ul><li>400 B.C. - Democritus thought matter could not be divided indefinitely.
350 B.C - Aristotle modified an earlier theory that matter was made of four “elements”: earth, fire, water, air.
Aristotle was wrong. However, his theory persisted for 2000 years.</li></li></ul><li>The Rise of Modern Chemistry<br />The Greek idea of the 4 basic elements was not disputed until the mid 1600s<br />Robert Boyle proposed that elements are substances that cannot be chemically decomposed into simpler substances. Earth, air, fire and water could not be called elements<br />In 1774 Joseph Priestly discovered a gas in which substances burned easily, Antoine Lavoisier named the gas Oxygen<br />Boyle<br />Priestly<br />
John Dalton<br /><ul><li>1800 -Dalton proposed a modern atomic model</li></ul> based on experimentation not on pure reason.<br /><ul><li>All matter is made of atoms.
His ideas account for the law of conservation of mass (atoms are neither created nor destroyed) and the law of constant composition (elements combine in fixed ratios).</li></li></ul><li>Reaction of the Day 9/9/10<br />Table sugar + sulfuric acid Carbon + H20<br />H2SO4<br />C12H22011(s) 12 C (s) + 11 H2O (g)<br />
Ch 2 - Matter<br />Matter – anything that takes up space and has mass<br />
Chemical and Physical Properties of Matter<br />Physical properties – color, shape, texture, odor, taste, electrical conductivity, and density<br />density – how closely packed the molecules are <br />malleable – substances that can be easily hammered into shapes<br />ductility – substances that can be stretched into wires<br />conductivity – substances that can transfer heat or electricity<br />Chemical properties – describe how matter acts in the presence of other materials<br />
What is each picture modeling? <br />Density, malleability, ductility, conductivity<br />
Physical vs. Chemical Change<br />Physical Change<br />Atoms do not rearrange<br />Only physical properties change. Chemical properties do not change.<br />Physical changes are generally easy to reverse.<br />No energy is produced by the substance.<br />Chemical Change<br />Atoms are rearranged into different molecules<br />Both physical and chemical properties are changed<br />Changes are not reversible without another reaction<br />Energy is often produced ( fire or heat, for example)<br />
Identify each of the following as a Physical or Chemical Change.Put a P next to Physical Changes and a C next to Chemical Changes<br />1. A piece of wood burns to form ash. <br />2. Water evaporates into steam. <br />3. A piece of cork is cut in half.<br />4. A bicycle chain rusts. <br />5. Food is digested in the stomach. <br />6. Water is absorbed by a paper towel. <br />7. Hydrochloric Acid reacts with zinc. <br />8. A piece of an apple rots on the ground. <br />9. A tire is inflated with air. <br />10. A plant turns sunlight, CO2, and water into sugar and oxygen. <br />11. Sugar dissolves in water. <br />12. Eggs turn into an omelette. <br />13. Milk sours. <br />14. A popsicle melts. <br />15. Turning brownie mix into brownies. <br />
The Division of Matter<br />Two major categories:<br /> 1) pure substances - consists of only one type of matter, which cannot be separated into other kinds of matter by any physical processes. Ex: Olive oil<br /> 2) mixtures – material that can be separated by physical means into two or more pure substances. Ex: Oil and vinegar salad dressing<br />
Two Types of Mixtures<br />Heterogeneous – physical combinations of pure substances that show two or more distinct phases. Ex: oil & vinegar dressing, granite has quartz & mica<br />Homogeneous – (solution) physical combinations of pure substances that show one distinct phase, the physical properties appear to be the same throughout. Ex: dough & air<br />
Elements and Their Symbols<br />Element - pure substance that cannot be broken down into simpler substances<br />
Elements and Their Symbols<br />Atoms – smallest particles that maintain the physical and chemical characteristics of an element<br />Monoatomic elements – elements that do not naturally combine or bond together. Ex: Ne, He, Ar<br />Diatomic elements - elements that bond into two-atom units. Ex: O2, H2<br />Polyatomic elements – elements composed of multi-atom units. Ex: S8<br />
Elements and Their Symbols<br />Symbol – letter given to represent the name of each element<br />H – hydrogen<br />O – Oxygen<br />Ca – Calcium<br />Mg – Magnesium<br />Mn – Manganese<br />Na - Sodium <br />
Compounds and Their Formulas<br />Compounds are made up of atoms from two or more different elements, chemically bonded together<br />Formulas tell the type and number of atoms that are present in compounds<br /> Common Compounds and Their Formulas<br />
Sample Problems<br />How many atoms of each element are present in each of the following groups? <br />Na2S2O3<br />Mg(NO3)2<br />5 Fe2O3<br />
Molecule<br />The smallest independent units of compounds <br />Consist of two or more atoms that are chemically bonded together<br />Ex: H20, NH3, H2SO4<br />Homework: Section Review Questions 2A, <br />pg 29, #1-3<br />
2B Energy in Matter<br />Every chemical reaction either releases or absorbs energy<br />Exothermic reactions – release energy (get hot) Ex: lighting a match<br />Endothermic reactions – absorb energy (get cold) Ex: ice pack<br />
Energy – the ability to do work<br />There are many forms of energy<br />Chemistry is concerned with the relationship among chemical, thermal, electrical and nuclear energy<br />
Energy Conservation<br />Thermodynamics – the study of energy flow<br />First Law of Thermodynamics or Law of Conservation of Mass-Energy –matter and energy can neither be created nor destroyed, simply changed from one form to another<br />Second Law of Thermodynamics – during any energy transformation, some energy goes to an unusable form<br />
Energy Conservation<br />Entropy – randomness or disorder of a system<br />There is a tendency for all natural processes to increase in entropy (disorder)<br />
Heat, Energy & Temperature<br />Kinetic Energy – energy of motion<br /> All matter contains particles that are moving<br />Thermal Energy – sum of all the kinetic energy of an object<br />Temperature measures the average kinetic energy of all the particles in a sample<br />Heat – thermal energy that is transferred from one object to another<br />Amount of heat transfered between objects is determined by the temperature difference between then and the mass of the hotter object<br />
Which contains more thermal energy?<br />A teaspoon of boiling water or a bathtub full of lukewarm water<br />
The Measurement of Energy<br />Joule – standard unit of measurement for energy<br />BTU – English unit of measurement for thermal energy, the amount of heat required to raise one pound of water by one degree Fahrenheit<br />Calorie – amount of energy required to raise the temperature of one gram of water one degree Celsius<br />1 cal = 4.184 J<br />
Temperature Scales<br />Celsius scale – freezing point of water is 0◦ C<br /> boiling point of water is 100 ◦ C<br />Kelvin scale – uses absolute zero (point at which molecules no longer move) as the zero point<br /> freezing point of water is 273 K<br /> boiling point of water is 373 K<br />Fahrenheit scale – freezing point of water is 32◦F<br /> boiling point of water is 212 ◦F<br />
Conversion between scales<br />K = ◦ C + 273 ◦ C = K - 273 <br />◦ F = (1.8 x ◦ C) ◦ C = (◦ F-32)/1.8<br />Sample Problem: The weatherman announces that the high for the day is expected to be 33 ◦ C What is this temperature on the Kelvin scale and the Fahrenheit scale?<br />Homework: Section Review Questions 2B<br />Pg 36, questions 1 - 4<br />
Phase Changes of Matter<br />Condensation –gas to liquid<br />Vaporization – liquid to gas<br />Freezing – liquid to solid<br />Melting –solid to liquid<br />Sublimation – solid to gas<br />Deposition – gas to solid<br />
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