2.1 Observable Properties of Matter

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2.1 Observable Properties of Matter
Ms. Wells, Science

Property 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 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 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 Density

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 = 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
Describe how substances form into new substances Examples: rusting, combustibility (burning), tarnishing, sometimes cooking, etc. Chemical REACTIONS = Chemical Changes

Physical 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 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 Changes
Precipitates forming (new solids from different liquid substances)

Pictures of Chemical Changes
Water and salt of sweat reacts with oils and substances on your skin = body odor

THE END OF 2.1 Properties of Matter in Matter and Energy