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