Ways of classification of matter Composition or physical state Matter Anything that takes up space or has mass weight Water solid molecules packed together rigid maintains volume does Solid liquid gas based on the characteristics it exhibits not flow liquid more loosely packed more mobile flows not compressible assumes container s shape gas even more loosely packed and mobile volume is not exact compressible flows assumes container s shape Classification of matter by composition Pure substance matter whose composition does not change from one sample to another Made of single atom or molecule Because the composition is always the same all samples have same characteristics Mixtures matter whose compositions may vary from one sample to the next Multiple types of particles homogenous vs heterogenous Samples may show different properties Solid mixture jewelry Gaseous air Liquid milk Changes in Matter Physical changes changes that alter state or appearance of matter without altering composition Boiling melting condensing Chemical changes changes that alter composition of the matter Rusting burning changing color During chemical change the atoms that are present rearrange into new molecules but all of the original atoms are still present Properties of matter Physical characteristics of matter that can be changed without changing its composition Characteristics that are directly observable Boiling point density Chemical characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy Characteristics that describe the behavior of matter Intensive and extensive properties Extensive properties whose value depends on quantity of matter Cannot be used to identify what type of matter something is Ex Volume mass Intensive properties whose value is independent of the quantity of the matter Used to identify what type of matter something is Energy Identical intensive properties usual mean they are the same All matter possesses energy Kinetic energy of motion Potential energy stored in matter and arises from electrostatic attractive forces between atoms molecules and subatomic particles Energy can be converted from one for to another Temperature average kinetic energy of the particles of the substance Energy always flows from hot to cold Scales Celsius Fahrenheit kelvin Conversion C F 32 1 8 K C 273 15 0K 459 F and 273 15 C Boiling point 212 F 100 C 373 K When temperature of Fahrenheit and Celsius is the same The standard units A set of international standard units for comparing all out measurements is called the SI units Quantity length mass time temp Related units in SI system Related to standard unit by power of ten Power of 10 is indicated by prefix multiplier Prefix multipliers are always the same regardless of standard unit Measurements reported with a unit that is close to the size of the quantity being measured Density Ratio of mass extensive property to volume extensive property Intensive property Solids g cm 3 1cm 3 1 mL Liquids g mL Gases g L Volume of solid can be determined by water displacement Archimedes principle Density solids liquids gases Except ice is less dense than liquid water Heating an object generally causes it to expand therefore density changes w temperature What is measurement Quantities observation Comparison to an agreed standard Every measurement has a number and a unit Significant figures The non place holding digits in reported measurement Some zeroes are there to hell you locate decimal point Tell us range of values to expect for repeated measurements The more sig figs the smaller range of value is 12 3 has 3 sig figs and it s range is 12 2 to 12 4 Counting sig figs 1 05 1 All non zero digits are significant Interior zeros are significant 2 A Leading zeros are not significant Trailing zeroes may or may not be sig A After a decimal point are sig B Before is sig if decimal point is written C End of number without decimal point is ambiguous and should be 3 4 avoided by using scientific notation Multiplication and division and addition and subtraction with significant figures 0 04450 m 4 sig figs 4 450 x 10 2 5 0003 has 4 sig figs 10 000 ambiguous When multiplying or dividing the result has the same number of sig figs as the measurement with lowest number of sig figs When adding or subtracting the result has the same number of decimal places as the measurement with the lowest number of decimal places When doing different kinds of operations do whatever is in the parentheses first evaluate the sig figs in intermediate answer then do the remaining steps Rounding When rounding to the correct number of sig figs if the number is after the place of the last sig fig is 0 to 4 round down 5 9 round up Drop all digits after last sig fig and leave last sig fig alone for 0 4 Drop all digits after last sig fig and increase last sig fig by one for 5 9 And insignificant zeros to keep value if necessary Uncertainty in measurements Comes from limitations of the instruments used for comparison the experimental design the experimenter and nature s random behavior To understand how reliable a measurement is we need to understand the limitations of the measurement Accuracy is an indication of how close a measurement comes to the actual value of the quantity Equations and dimensional analysis Always write every number with its associated unit Always include units in your calculations Using units as a guide to problem solving is called dimensional analysis Units as you can be operated on the same way as numbers Cm x cm cm 2 Cm cm cm Cm cm 1 Systematic approach to problem solving Sort info from problem Design strategy to solve problem Apply steps in plan to solve problem Check answer