Chemical Properties
Chapter 2 Section 3
Chemical Properties
• A property of matter that describes a
substance’s ability to participate in
chemical reactions is a chemical property.
• When wood is burned, smoke and ash are
created. These have very different
properties than the wood.
• Two types of chemical properties are
flammability and reactivity.
Flammability
• The ability of a substance to burn is
flammability.
• Wood is flammable. It can burn.
• Smoke and ash, created from a burning
piece of wood, are unable to burn. They
are nonflammable.
• Rubbing alcohol and oxygen are also
flammable. They will burn.
Reactivity
• The ability of two or more substances to
combine and form new substances is
reactivity.
• An iron nail can react with oxygen in the
air to form rust, or iron oxide.
• Chrome, which is nonreactive with
oxygen, will not rust.
Comparing Physical & Chemical
Properties
• Physical properties can be identified
without changing the identity of the
substance.
• You can observe the physical properties of
matter without changing the matter.
• Examples of physical properties are
density, shape, and state.
• Chemical properties are not as easy to
observe.
Comparing Properties
• You can only see that wood is flammable
when it is actually burning.
• You can only see that an iron nail is
reactive with oxygen after it has rusted.
Characteristic Properties
• Properties that are most useful in identifying a
substance are characteristic properties.
• These properties are always the same no matter
what size the sample is.
• Some characteristic properties are physical, like
density and solubility.
• Others are chemical properties, like flammability
and reactivity.
Chemical Changes
• A chemical change happens when one or
more substances change into new
substances that have new and different
properties.
• Some clues that chemical changes are
taking place are changes in color or odor,
heat being produced, fizzing, foaming,
sound, and/or light.
Physical vs. Chemical Changes
• Physical changes do not change the
composition of the substance.
• Grinding baking soda into a fine powder is
a physical change. The substance is still
baking soda.
• Mixing baking soda and vinegar is a
chemical change. A new substance is
formed.