Reactions and Interactions are the things that happen all the time
around you and inside of you. Salt dissolving in water, plants using
sunlight to make food and oxygen, static electricity making your
socks stick together in the dryer, and candles burning are all
examples of reactions and interactions.
Interactions involve changes in
the physical properties of matter. Physical properties are
those that can be measured or experienced without altering the
identity of the matter. Physical properties include size, volume,
density, color, odor, taste, and texture. Physical properties also
include things such as phase (solid, liquid or gas), particle size
and ability to dissolve.
Physical properties can be observed,
measured and even changed through physical changes. In other
words, physical changes are those that alter the appearance of
matter, but not the identity of matter. For example, melting ice and
then boiling the water produced causes a change in the appearance of
water, but both ice and steam are water. Dissolving salt in water is
another physical change. The salt can still be tasted in the mixture
created will still taste like salt and if the water evaporates the
salt regains its original form.
Reactions involve changes in the
chemical properties of matter. Chemical properties are those
that can only be measured or experienced by altering the identity of
matter. For instance, paper burns. This can only be seen by lighting
the paper on fire, resulting in the loss of the paper and the
creation of water, carbon dioxide and ash. Changes of this nature,
those that demonstrate chemical properties, are called chemical
changes.
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