8-30-10 - Chemistry is - study of matter, its properties,...

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Chemistry is - study of matter, its properties, the changes it experiences, and the energy associated with those changes. Basis is on observation; qualitative and quantitative. Law - We look for observations that are related to each other - try to make a generalized statement to summarize those observations - Law Hypothesis - Preliminary explanation for what we observe….WHY? Theory - formal explanation of a law…Summarizes the WHY? Often theories are expressed in Models - simplified version of what is being studied. What are the submicroscopic reasons? Solid phase (state); “Law” : Fixed shape, fixed volume, incompressible, typically most dense. “Theory”: components are not moving (translational), components are touching (closely packed). Chemistry - study of matter, its properties, the changes (delta symbol) it goes through and NRG (energy) associated with those changes. Matter - anything that has mass and occupies space (has volume). Physical Properties - observed without changing the make-up of the sample of matter. Example: state (phase), density, color, luster, magnetic properties, conduction of electricity and heat, solubility. Chemical Property - expressed when there is a change in composition. (One kind of matter is changed to another kind.)-”New” of different type of matter is produced when a chemical change occurs. Iron + Oxygen = Rust Iron - Shiny, malleable, magnetic Oxygen - supports combustion Rust - dull, brittle, not magnetic - different “stuff” different properties Composition of Sample Substance - Single type of matter. Fixed and unique set of properties Mixture - two or more substances. Variable properties depending on relative ratios of substances in sample. Properties of substances are not lost. Components can be separated using physical methods. Element and Compound - Elements are made of one type of atom. Compounds are made from two or more different elements in a fixed ratio. Energy associated with changes (physical or chemical) most typically experienced as HEAT. Heat can be related to kinetic energy as well as potential energy. Kinetic Energy - energy based on motion. Solid - particles don’t move much. Liquid - particles move past one another. Gas - random motion. To go from solid to liquid to gas you have to add energy in. Evaporation: cooling process. Liquid pulls energy from you to turn into a gas…you feel cooler. Potential Energy - potential to do work based on position. (tom and jerry…bowling ball dropping from a shelf - height of bowling ball and mass of ball related to amount of potential energy. In chemistry we have particles with charge that are separated (higher apart particles have more potential energy) Oppositely charged particles attract each other at shorter separations lower energy.
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Heat - thermal energy that flows from warmer to colder until thermal equilibrium. Temperature changes are the observable factor in heat flow.
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8-30-10 - Chemistry is - study of matter, its properties,...

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