2.1 Observable Properties of Matter2.1 Observable Properties of Matter
Ms. Wells, Science
Property TypesProperty Types
• Physical: properties that can be observed without changing the IDENTITY of the matter
• Chemical: property of a substance that changes it into a NEW substance (changes the identity of the substance)
Examples of Physical PropertiesExamples of Physical Properties
• Volume, mass, color, texture, shape and density
• Great example:• Stretching a rubber band may change its color
and shape, but its still made of rubber and is still a rubber band!
More about DensityMore about Density
• Density = amount of matter (mass) in a certain amount of space (volume)
• Density is constant (does not change for one substance)
• Different substances = different densities
U.S. Population DensityU.S. Population Density
Calculating Density (D)Calculating Density (D)
• Formula: D = m / V• Mass (m) = kilograms (kg) or grams (g)• Volume (V) = cubic centimeters (cm3)
• Sooo…. Units for density are g/ cm3
• Said “grams per cubic centimeters”
The Clay Example: Density = ConstantThe Clay Example: Density = Constant
• You have a 200g piece of clay with volume of 100 cm3
• V = 200g/100 cm3
• V = 2 g/cm3
• If you break it in half, you have 2 pieces of clay that are 100g and 50 cm3 each• V = 100g/50cm3
• V = 2 g/cm3
• SAME DENSITY!
Examples of Chemical Properties and Changes
Examples of Chemical Properties and Changes
• Describe how substances form into new substances
• Examples: rusting, combustibility (burning), tarnishing, sometimes cooking, etc.
• Chemical REACTIONS = Chemical Changes
Physical ChangesPhysical Changes
• Any change that does not change the actual substance itself
• Changes in states of matter are physical (melting ice, etc.)
• Other examples:• Breaking an object• Wool on a sheep
or a wool sweater is still wool
Signs of a Chemical ChangeSigns 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 often
• New solids from liquids (called precipitates) – clams make shells by mixing seawater substances and substances in their bodies
Pictures of Chemical ChangesPictures of Chemical Changes
• Precipitates forming (new solids from different liquid substances)
Pictures of Chemical ChangesPictures of Chemical Changes
• Water and salt of
sweat reacts with oils
and substances on
your skin = body odor
THE END OF 2.1Properties of Matter
inMatter and Energy
THE END OF 2.1Properties of Matter
inMatter and Energy