Chapter 1 Chemistry The study of properties of materials and the changes they undergo Matter has mass takes up space made up of elements Property characteristic of matter Either pure elements of combination of elements Atom building block of an element about 117 total Molecule 2 or more atoms connected can be the same or different atoms Properties are determined by type of atoms and how they connect shape or structure of molecules 3 states of Matter Gas no specific volume size or shape molecules move fast and are spread out Liquid no shape has specific volume molecules are closer and moving around Solid specific shape and volume molecules are packed close and don t move Pure Substance v Mixtures compounds only 1 element distinct properties combo of 2 or more elements each element retains its own chemical ID Accuracy how well you hit the goal Precision how consistently you hit the goal Mixture 2 types of elements compound Homogenous uniform composition contains only 1 type of Heterogeneous different composition properties and appearances can contain a combo of different compounds and atoms ALL SOLUTIONS ARE HOMOGENEOUS MIXTURES AND ALL HOMOGENEOUS MIXTURES ARE SOLUTIONS Chemical how reactive a substance is what type of substance is produced from the rx Matter has 2 types of properties Physical color density odor melting point Chemical Properties Intensive Prop is Describes composition of a substance doesn t matter how much of it there Extensive Prop Quantity of a substance matters how much there is measured in mass volume etc 2 extensive mass and volume can combine to make intensive density Physical changes physical state or phase changes Chemical changes elemental composition changes 3 main types of separation of mixtures Filtration Distillation Chromatography CHECK OUT TABLES 1 4 1 5 FOR UNITS AND PREFIXES Length Meter m 1 09 yd 1000m 1 kilometer 1m 1000mm Mass Kilogram kg 2 2 lbs 1kilogram 1000 grams Volume Liter L 1m 3 1000L 1 liter 1000mL Density Mass Volume units grams per cubic cm or grams per milliliter changes with temperature Significant Figures how many digits in a number used to give more info about the number the more digits the more certain the measurement location of decimal point doesn t matter Rules Leading zeros are NOT significant 0 0255 Captive zeros ARE significant 20 502 Trailing zeros AFTER a decimal place ARE significant 25 200 Trailing zeros BEFORE a decimal place CAN BE significant Convert to scientific notation to check number of sig figs number of times you move the decimal number of sig figs Math and Sig figs Addition Subtraction Answers must have the fewest decimal places Mult Div Answers must have the fewest sig figs Dimensional Analysis Used to convert a number from one unit to another units should cancel out except for the unknown units cancel out like variables in math KEY THINGS Phases Physical chem properties SI units and prefixes Significant figures Dimensional analysis