2.2 Physical Properties
Examples of Physical Properties
A physical property is any characteristic of a
material that can be observed or measured
without changing the ________________ of the
substances in the material.
Viscosity, conductivity, malleability,
hardness, melting point, boiling point, and
density are examples of physical properties.
2.2 Physical Properties
Examples of Physical Properties
Viscosity
The tendency of a liquid to
keep from________is called its
viscosity.
• Thick liquids, such as corn
syrup and honey, have a high
viscosity.
• Thin liquids, such as vinegar
and water, have a low
viscosity.
2.2 Physical Properties
Examples of Physical Properties
Conductivity
A material’s ability to allow_____to flow
is called conductivity.
• Materials that have a high conductivity,
such as metals, are called conductors.
• Good conductors of heat are usually also
good conductors of electricity.
2.2 Physical Properties
Examples of Physical Properties
Malleability
The ability of a solid to be___________without shattering is
malleability.
• Most metals, such as gold, are malleable.
• An ice cube or piece of glass breaks into small pieces
when struck with a hammer. Solids that shatter when
struck are brittle, not malleable.
2.2 Physical Properties
Examples of Physical Properties
Hardness
One material can____________another material if it is
harder than the other material.
• A kitchen knife can scratch a copper sheet because
stainless steel is harder than copper.
• The material used to sharpen the knife blade must be
harder than stainless steel. Diamond is the hardest known
material.
2.2 Physical Properties
Examples of Physical Properties
Melting and Boiling Points
The temperature at which a material changes state is
a physical property.
• The temperature at which a substance changes
from solid to liquid (______) is its melting point.
• The temperature at which a substance changes
from liquid to gas (________) is its boiling point.
2.2 Physical Properties
Examples of Physical Properties
Melting and Boiling Points
Which of these substances are liquids
at room temperature (20C, or 68F)?
Answer: octane,
water, and
______________
2.2 Physical Properties
Examples of Physical Properties
Density
The ratio of the mass of a substance to its volume is
its density.
• Density can be used to test the___________of a
substance.
• Silver has a density of 10.5 g/cm3. A coin with a
density of 9.9 g/cm3 is not made from silver, or it
contains substances in addition to silver.
2.2 Physical Properties
Using Physical Properties
Using Properties to Identify Materials
Physical properties are used to identify a material,
to choose a material for a specific purpose, or to
separate the substances in a mixture.
To ______________:
• Decide which properties to test.
• Do tests on a sample of the unknown material.
• Compare the results with the data reported for known
materials.
2.2 Physical Properties
Using Physical Properties
Using Properties to Choose Materials
To___________which materials are chosen for which
uses:
• For example, shoelaces must be flexible, that is
they must be able to bend without breaking.
• They must also be durable, that is, they must be
able to withstand repeated use.
2.2 Physical Properties
Using Properties to Separate Mixtures
Filtration and distillation are two common
separation methods for mixtures.
Filtration
You can separate hot tea from loose tea leaves by
pouring the mixture through a strainer.
Filtration is a process that separates materials based
on the size of their_____________________.
2.2 Physical Properties
Using Properties to Separate Mixtures
These students filter (sift) dirt through a wire screen to
locate small objects. Particles of dirt are small enough
to pass through the holes, but objects such as broken
bits of pottery are too large.
2.2 Physical Properties
Using Properties to Separate Mixtures
Distillation
Sometimes all the particles in a solution
are small enough to pass through a filter.
Distillation is a process that separates
the substances in a solution based on
their _______________________.
2.2 Physical Properties
Recognizing Physical Changes
The change of water from a liquid to a gas during
boiling is a physical change.
A physical change occurs when some of the
properties of a material change, but the substances in
the material ________________________________.
During a physical change, the size and shape of a
material can change but not the____________. Some
examples include
• melting butter in a pan
• crumpling a piece of paper
• slicing a tomato
2.2 Physical Properties
Recognizing Physical Changes
Some but not all physical changes can be
____________. Braiding hair is a reversible
change. Cutting hair cannot be reversed.