CHM 1045 Final Study GuideChapter 1Atoms are submicroscopic particles are the fundamental building blocks of all matterMolecules two or more atoms attached together attachments are called bonds molecules come in different shapes and patternsChemistry is the science that seeks to understand the behavior of matter by studying the behavior of atoms and moleculesHypothesis • a tentative interpretation or explanation for a single or small number ofobservations falsifiable – confirmed or refuted by other observations tested by experiments – validated or invalidatedScientific law • when similar observations are consistently made, it can lead to a scientific law a statement of a behavior that is always observed summarizes past observations and predicts future ones Law of Conservation of MassTheory a general explanation for the manifestation and behavior of all natureClassification of matter• matter is anything that has mass and occupies space• we can classify matter based on it’s physical state (whether it’s solid, liquid, or gas) Solid: fixed shape, fixed volume, can’t compress and doesn’t flowLiquid: indefinite shape, fixed volume, can’t compress and can flowGas: indefinite shape, indefinite volume, can compress, and flowsSolids • the particles in a solid are packed close together and are fixed in position though they may vibrate• the close packing of the particles results in solids being incompressible• the inability of the particles to move around results in solids retaining their shape and volume when placed in a new container, and prevents the particles from flowingLiquids • the particles in a liquid are closely packed, but they have some ability to move around • the close packing results in liquids being incompressible• but the ability of the particles to move allows liquids to take the shape of their container and to flow – however, they don’t have enough freedom to escape and expand to fill the containerGases • in the gas state, the particles have complete freedom from each other• the particles are constantly flying around, bumping into each other andthe container• in the gas state, there is a lot of empty space between the particles. Thus, the particles can be squeezed closer together – gases are compressible• because the particles are moving freely, gases expand to fill and take the shape of their container, and will flowMatter: pure substance vs. mixturePure substance: 1) made of one type of particleCHM 1045 Final Study Guide2) all samples show the same characteristics Mixture1) made of multiple types of particles2) samples may show different characteristicsPure substances: element vs. compoundElement:1) made of one type of atom (some elements found as multi-atom molecules in nature)2) combine together to make compoundsMixture1) made of one type of molecule, or array of ions2) molecules contain 2 or more different kinds of atomsElements substances that cannot be broken down into simpler substances by chemical reactionsCompounds substances that can be decomposedMixtures: heterogeneous vs. homogeneousHeterogeneous1) made of multiple substances, whose presence can be seen2) portions of a sample have different composition and propertiesHomogeneous1) made of multiple substances, but appears to be one substance2) all portions of a sample have the same composition and propertiesHomogeneous • mixture that has uniform composition throughout every piece of a sample has identical characteristics, though another sample with the same components may have different characteristics atoms or molecules mixed uniformlyHeterogeneous • mixture that does not have uniform composition throughout contains regions within the sample with different characteristicsatoms or molecules not mixed uniformlyPhysical changes changes that alter the state or appearance of the matter without altering the composition-Boiling -Evaporation-Sublimation-Freezing-melting-condensing-dissolvingChemical Changes changes that alter the composition of the matter during the chemical change, the atoms that are present rearrange into new molecules, but all of the original atoms are still present-rusting-change in matter-burningStandard units Length = meter (m)Mass = kilogram (kg)CHM 1045 Final Study GuideTime= second (s)Temperature= Kelvin (K)Related to standard unit by a power of tenMega- x10^6Kilo- x10^3Deci- x10^-1Centi- x10^-2Milli- x10^-3Nano- x10^-9Celsius to KelvinK =° C+273 . 15Volume -relationship betweencm3 and mL• Measure of the amount of space occupied 1 cm3 = 10-6 m3 1 mL = 1 cm3 1 L = 1000 mL Extensive property • mass and volume are extensive properties the value depends on the quantity of matter extensive properties cannot be used to identify what type of matter something isIntensive property • Ratio of mass: volume is called density and is an intensive property (value independent of the quantity of matter)Density • two main physical properties of matter Solids = g/cm3 Liquids = g/mL Gases = g/L• Density : solids > liquids >>> gases except ice is less dense than liquid water!Density= mass/volume• For equal volumes, denser object has larger mass• For equal masses, denser object has smaller volume• Heating an object generally causes it to expand, therefore the density changes with temperatureCan use density as a conversion factor between mass and volume Significant figures 1) All non-zero digits are significant (1.5 has 2 sig. figs.) 2) Interior zeros are significant (1.05 has 3 sig. figs.) 3) Leading zeros are NOT significant (0.001050 has 4 sig. figs. Because = 1.050 x 10-3) 4) Trailing zeros may or may not be significant1) Trailing zeros after a decimal point are significant (1.050 has 4 sig. figs.)2) Zeros at the end of a number without a written decimal point are ambiguous and should be avoided by using scientific notation if 150 has 2 sig. figs. then 1.5 x 102 but if 150 has 3 sig. figs. then 1.50 x 102 Multiplication/divisionwith sig figs-Result has same number of sig figs as the fewest number of sig figsAdding/subtracting SF Fewest number of decimal placesCHM 1045 Final Study GuideAccuracy an indication of how close a measurement comes to the actual value of the quantityPrecision an indication of how reproducible a measurement isDimensional analysis:given unit×desired unitgiven unit=desired unitCHAPTER 2Dalton’s atomic theory 1) Each element is
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