CHM 1045 Final Study Guide Theory Classification of matter a general explanation for the manifestation and behavior of all nature matter is anything that has mass and occupies space we can classify matter based on it s physical state whether it s solid Chapter 1 Atoms Molecules Chemistry Hypothesis Scientific law Solids Liquids Gases are submicroscopic particles are the fundamental building blocks of all matter two or more atoms attached together attachments are called bonds molecules come in different shapes and patterns is the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules a tentative interpretation or explanation for a single or small number of observations falsifiable confirmed or refuted by other observations tested by experiments validated or invalidated 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 Mass liquid or gas Solid fixed shape fixed volume can t compress and doesn t flow Liquid indefinite shape fixed volume can t compress and can flow Gas indefinite shape indefinite volume can compress and flows 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 flowing 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 container in the gas state the particles have complete freedom from each other the particles are constantly flying around bumping into each other and the 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 flow Matter pure substance vs mixture Pure substance 1 made of one type of particle CHM 1045 Final Study Guide Pure substances element vs compound Mixture Element Mixture 2 all samples show the same characteristics 1 made of multiple types of particles 2 samples may show different characteristics 1 made of one type of atom some elements found as multi atom molecules in nature 2 combine together to make compounds 1 made of one type of molecule or array of ions 2 molecules contain 2 or more different kinds of atoms Elements Compounds Mixtures heterogeneous vs homogeneous substances that cannot be broken down into simpler substances by chemical reactions substances that can be decomposed Heterogeneous 1 made of multiple substances whose presence can be seen 2 portions of a sample have different composition and properties Homogeneous Heterogeneous mixture that does not have uniform composition throughout Homogeneous Physical changes Chemical Changes 1 made of multiple substances but appears to be one substance 2 all portions of a sample have the same composition and properties 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 uniformly contains regions within the sample with different characteristics atoms or molecules not mixed uniformly changes that alter the state or appearance of the matter without altering the composition Boiling Evaporation Sublimation Freezing melting condensing dissolving 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 Standard units rusting change in matter burning Length meter m Mass kilogram kg CHM 1045 Final Study Guide Time second s Temperature Kelvin K Related to standard unit by a power of ten Mega x10 6 Kilo x10 3 Deci x10 1 Centi x10 2 Milli x10 3 Nano x10 9 K C 273 15 Measure of the amount of space occupied 1 cm3 10 6 m3 1 mL 1 cm3 1 L 1000 mL Celsius to Kelvin Volume relationship between cm3 and 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 is Intensive property Density Ratio of mass volume is called density and is an intensive property value independent of the quantity of matter 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 temperature Can use density as a conversion factor between mass and volume 1 All non zero digits are significant 1 5 has 2 sig figs Interior zeros are significant 1 05 has 3 sig figs 2 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 significant 1 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 Significant figures Multiplication division with sig figs Adding subtracting SF Fewest number of decimal places Result has same number of sig figs as the fewest number of sig figs CHM 1045 Final Study Guide Accuracy Precision Dimensional analysis an indication of how close a measurement comes to the actual value of the quantity an indication of how reproducible a measurement is given unit desired unit desired unit given unit CHAPTER 2 Dalton s atomic theory 1 Each element is composed of tiny indestructible particles called atoms 2 All atoms of a given element are identical having the same size mass and chemical properties The atoms of one element are different from the atoms of all other elements 3 Atoms combine in simple whole number ratios to
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