2 Physical PropertyPhysical property = a characteristic of matter that can be observed or measured without changing the identity of the substanceEx: mass volumedensity hardnesscolor malleabilityductility lustersolubility viscositymelting, boiling, freezing pointsability to conduct heat & electricity
3 MalleabilityMalleability = capable of being shaped or formed (metals are malleable)
4 DuctilityDuctility = ability to be pulled or stretched into wires
7 Viscosity Viscosity = “liquid thickness” The thicker the liquid the slower it will pour
8 Density Density = mass/volume D = m/V Units for density include (but there are more!)g/mL or g/cm3kg/L or kg/m3Density can be used to identify unknown matter because density is a property of matter that doesn’t depend on size!Ex: Lead has a density of g/mLTherefore, all pure samples of lead will have a density of g/mLEx: Copper has a density of 8.92 g/mLTherefore, all pure samples of copper will have a density of 8.92 g/mL
9 Which is more dense liquid water or frozen (solid) water???? DensityDensity of H2O at 20 °C (68 °F)= g/mL (it’s ok if we round to 1.00 g/mL)Density of H2O at 0 °C (32 °F) = 0.92 g/mLWhich is more dense liquid water or frozen (solid) water????Liquid water! This is why ice floats…and fish don’t die in lakes in the winter!
10 DensityIf an object is more dense than water it will generally sink in waterIf an object is less dense than water it will generally float in waterEx: If mercury (D = 13.6 g/mL), copper (D = 8.92 g/mL), and water at 20 °C (D = 1.00 g/mL) are combined what will be the order of the layers based on their densities?
12 Physical PropertyPhysical properties can be described further as extensive or intensive.Extensive Property = property dependent of the amount of substance present or sizeSIZE MATTERS!Ex: mass, volume, lengthIntensive Property = property independent of the amount of substance present or sizeEx: density, melting point, boiling point, freezing point, malleability, ductility, viscosity, all chemical propertiesSIZE DOESN’T MATTER!
13 Intensive or Extensive? MassColorDensityShapeMelting pointTexture
14 Physical ChangesPhysical changes = changes that alter matter but don’t change its chemical composition (make-up)Change appearance but not chemical make-upEx: cut carrots shred paperchop wood grind coffeebreak glass melt candle waxboil water freeze alcoholdissolve NaCl in water
16 Chemical PropertyChemical property = the ability or inability of a substance to react
17 Chemical ChangesChemical change = any change that causes one material to turn into a new material with a different chemical make-upEx: Na+ reacting with Cl-road kill decomposingbananas rottinggrapes fermentingiron rustingcopper oxidizingcooking eggsgrass growing
18 Chemical ChangesChemical changes can also be called a chemical reactions.Chemical reactions can be represented by chemical equations.Reactants = starting substance(s)Products = new or end substance(s)Reactants and products separated by an arrowReactants → Products
19 Chemical ChangesLaw of Conservation of Mass = matter is neither created nor destroyed in ordinary chemical reactions, it’s simply rearranged.The mass (or amount) of the reactants and the products is equal.Ex: 2 NaN3 Na N2150g 50g gNa2SO ZnBr2 ZnSO NaBr100g g 130g g
20 Chemical change action words React ExplodeDecompose RotFerment RustOxidize CorrodeCook (with heat) Grow
21 Chemical Change Signs of a chemical change or reaction 1. Temperature changeExothermic reaction = a reaction that gives off energy- warm/hot to touchEndothermic reaction = a reaction that absorbs energy- cool/cold to touch2. Spontaneous change in colorEx: like when things rust, rot, burn3. Gas produced4. Odor given off5. Formation of precipitate (solid)
22 CHEMICAL OR PHYSICAL CHANGE? Baking cookiesBoiling waterDissolving saltBurning firewoodMilk spoilingMetal rustingTearing paperMelting ice