Chemistry classnotes

Chemistry classnotes - August 27, 2007 [Chapter 1 class]...

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August 27, 2007 [Chapter 1 class] Chemistry: Study of matter and energy and the change they undergo (change where matter is/how connected “build molecules”) Scientific method: 1 observe 2 hypothesis 3 Skeptical of hypothesis (can never prove anything completely) a take another view of hyp. 4 Devise experiment (if hyp looks good) 5 test and revise hyp if necessary 6 (after multiple successes) upgrade to theory (cannot be law, theory can be disproved) Matter: anything that has mass and takes up space (14.7 lbs/1 in^2 of mass in atmosphere) electrons have mass, protons heavier—always take into account in chem., and how close can get atoms together a. Size -Macroscopic-see it, we live in this level -Microscopic-need a microscope (eg cell) -Particulate- (chemistry) need really special equipment, need something that sees things at the atomic level (work in this level) [August 29] Representations of molecules: 1. Formulas-atoms representing molecule (H 2 O) 2. Lewis diagram- diagram of how atoms oriented with each other (H-O-H) good for organic atoms, carbon/hydrogen 3. Models/symbols- represent particulate matter a. Ball and stick: show shape, compounds bent b. Space filling: relative size of atom to each other State of Matter -Amount of movement of molecule determines its state, more movement more likely gas. Less movement=solid Kinetic Molecular theory- all matter made up of tiny particles, hotter the molecules the faster they go, larger they are more energy needed to be put in *3 States of matter: 1. Gas: Shape varies, take on shape they’re in, volume changes (assuming container closed), no definite shape or volume 2. Liquid: shape varies, defined volume 3. Solid: defined shape and volume (see water in all 3 states, only compound) Physical Change: changes what something looks like without changing substance
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Chemical Change: changes the compound, can’t get original state back Pure Substance- made up of single molecule or atom (sugar, salt, 24 K gold) Impure Substance- (14 K gold) more than one substance Homogeneous- looks same throughout (water, milk) usually solutions, things made into liquids, gases also almost always homo Heterogeneous- doesn’t look the same throughout (cars, beach sand), usually mixed solids Separations- --Distillation- best way to separate liquid, liquid boils at different temp, if there is solid, solid left behind when water is distilled (oldest method) - -Filtration- based off size of compound and if it is a liquid and solid mix EX: iron and graphite mixed-use magnet to separate Elements… Substances that cannot be decomposed into stable pure substances -Compound: can be broken down Law of Constant Composition: Any compound is always made up of elements in the same proportion by mass EX: 100 g H 2 O 11.1 g H > True no matter where you are 88.9 g O [August 30] Electrical Character of Matter --Like gravity, magnetism is a force --matter can be charged, can get neg/pos, put a charge into system
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This note was uploaded on 04/07/2008 for the course CHEM 023 taught by Professor Morris during the Fall '08 term at Vermont.

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Chemistry classnotes - August 27, 2007 [Chapter 1 class]...

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