Presentation on theme: "2.1 Observable Properties of Matter"— Presentation transcript:
1 2.1 Observable Properties of Matter Ms. Wells, Science
2 Property TypesPhysical: properties that can be observed without changing the IDENTITY of the matterChemical: property of a substance that changes it into a NEW substance (changes the identity of the substance)
3 Examples of Physical Properties Volume, mass, color, texture, shape and densityGreat example:Stretching a rubber band may change its color and shape, but its still made of rubber and is still a rubber band!
4 More about DensityDensity = amount of matter (mass) in a certain amount of space (volume)Density is constant (does not change for one substance)Different substances = different densities
6 Calculating Density (D) Formula: D = m / VMass (m) = kilograms (kg) or grams (g)Volume (V) = cubic centimeters (cm3)Sooo…. Units for density are g/ cm3Said “grams per cubic centimeters”
7 The Clay Example: Density = Constant You have a 200g piece of clay with volume of 100 cm3V = 200g/100 cm3V = 2 g/cm3If you break it in half, you have 2 pieces of clay that are 100g and 50 cm3 eachV = 100g/50cm3V = 2 g/cm3SAME DENSITY!
8 Examples of Chemical Properties and Changes Describe how substances form into new substancesExamples: rusting, combustibility (burning), tarnishing, sometimes cooking, etc.Chemical REACTIONS = Chemical Changes
9 Physical ChangesAny change that does not change the actual substance itselfChanges in states of matter are physical (melting ice, etc.)Other examples:Breaking an objectWool on a sheepor a wool sweateris still wool
10 Signs of a Chemical Change Odor – new smell (rotting meat, burning smell)Temperature change – log goes from wood to ash, feel the heat!Color change – not always chemical, but oftenNew solids from liquids (called precipitates) – clams make shells by mixing seawater substances and substances in their bodies
11 Pictures of Chemical Changes Precipitates forming (new solids from different liquid substances)
12 Pictures of Chemical Changes Water and salt ofsweat reacts with oilsand substances onyour skin = body odor