2Chemistry The study of matter and how it changes Matter – anything that has mass and takes up spaceMass – resistance to change in motionTwo types of matter-Substance- PureMixture- more than one substance
3Two Kinds of Substances Elements- Simplest kind of matterCan’t be broken down furtherAll one kind of atom116 kinds of elementsEach has a 1 or two letter symbolEach behaves differentlyEverything else is built of them
4Two Kinds of Substances Compounds- Made of two elements chemically combinedAtoms stick together to make moleculesAll molecules of a compound are the sameThey mix in the same ratioCompounds behave completely differently from the elements that make them
11Molecules Most molecules form from different kinds of atoms A few elements form molecules tooO2N2H2Cl2F2I2S8P4
12Pure Substance Elements and compounds Only one kind of molecule or atomCompounds have specific amounts of their elementsCompounds are completely different from their elements
13Mixture Different substances mixed together Can be in any proportion Keeps the same properties as the things that make itKool-aidMix something sweet, something wet and something redGet something sweet, wet and red
14Two Types of Mixtures Heterogeneous- Different from place to place Not evenly mixedChocolate chip cookie, gravel, soilHomogeneous-The same throughoutEvenly mixedKool-aid, sea water, air
15Liquid Mixtures Miscible- Liquids that do dissolve in each other HomogeneousGasolineImmiscible-Liquids that don’t dissolve in each otherHeterogeneousOil and water
16Kinetic Theory Kinetic means motion Three main parts of the theory All matter is made of tiny particlesThese particles are in constant motion and the higher the temperature, the faster they moveAt the same temperature, heavier particles move slower.
17States of Matter Solid Particles are tightly packed Stuck to each other in a patternVibrate in placeCan’t flowConstant volume
18States of Matter Liquid Particles are tightly packed Able to slide past each otherCan flowConstant volume
19States of Matter Gas Particles are spread out Flying all over the placeCan flowVolume of whatever container their in
20Gases Fill the available space Particles moving at about 500 m/s Particles hitting things cause pressure
21Liquids Spread out on their own Fluids- gases and liquids both flow Viscosity- the resistance to flowThe better the molecules stick to each other, the more resistance
22Energy The ability change or move matter As you add energy to a liquid, the temperature goes upThe molecules move fasterEventually they will move fast enough to break free and become a gasThis is evaporation- the change from a liquid to gas
23Phases ChangesIf you change rapidly enough, the gas will form below the surface an boilCondensation- Change from gas to liquidAs you cool a gas the molecules slow downAs gas molecules slow down they stick together
24Phases Changes Molecules and atoms don’t change during a phase change the composition doesn’t changeThe mass doesn’t changeThe volume does changeOnly the attractions and motion change
25Law of Conservation of Mass In all changes, mass cannot be created or destroyedAll the mass you start with you end withIt might be hard to count
26Law of Conservation of Energy In all changes, energy cannot be created or destroyedAll the energy you put in, you get outIt might be hard to count
27Properties A property is a something that describes matter An adjectiveUsed to identify the matterUsed to distinguish between different types
28Chemical Properties Used to describe how substance reacts How it changesBy combining with other substancesOr breaking apartReactivity how a substance combines with other substancesThings like flammability, rusting, etc.
29Physical PropertiesCan be observed or measured without changing the compositionMelting point , boiling point, hardness, odor, ability to conduct electricity and heatDensity – how heavy something is for its sizeRatio of mass to volumeIf the density of substance is less than its surroundings, it floats
30Density Found by dividing the mass by volume D = m V Units of g/mL or g/cm3Water has a density of 1 g/mL
31DensityDMVCover up the one you are looking for to find the formula for the missing piece
32DensityMVDA piece of wood has a mass of 12 g and a volume of 16 cm3 What is its density?Steel has a density of 7.8 g/cm3. How much would 56 cm3 of steel weigh?What would the volume of the same mass of water be?
33Properties Allow us to identify substances Allow us to separate substancesDetermine uses
34Changes Two types- Physical Changes- no new type of matter is made All the molecules stay the sameChemical Change- a new type of matter is madeAtoms rearrange to make new elements or compounds
35Chemical Changes Completely new properties Products are not at all like the reactantsMakes new odor, color, etc.
36Physical Changes Might look a little different Keeps original propertiesChanging phasesMaking a mixtureCuttingGrindingDissolving
37Dissolving SugarWater molecules break apart and surround sugar moleculesAll the original molecules are still thereSugar gets so spread out that they don’t block light