1-Changes in Matter: Physical
Matter never stays the same - it either changes states or
changes components. When something changes in state or shape, it is said to have
undergone a physical change. When the chemical formula changes and creates a
new compound, the matter is said to have undergone a chemical change.
Physical Changes: When wood
burns, a chemical
change occurs, but when wood is heated up until it suddenly turns into a
liquid or a gas, a physical change happens. When an egg is cooked and becomes
rubbery, it has changed in the chemical make up. If you froze an egg, a
physical change would be witnessed.
What is the difference between cooking and
freezing an egg or burning and transforming wood? The answer is simple. When
you burn wood, carbon molecules are released and they join up with oxygen
in the air: a chemical change. Your cooked egg, however, has been
solidified by heat (very unnatural!), while the frozen egg is solid from the
cold.
For matter to interchange between the states of solid,
liquid,
and gas,
a physical change happens and is
interchange-able. Other kinds of physical changes are disolving a
solute, mixing a substance with another substance, cutting an object
into peices and/or molding the matter. As long as no new compounds are
created, there has been a physical change. Below is an
image of chlorine, as a gas and as a liquid. Bottom of vial=Liquid
Chlorine. Top of vial=Chlorine gas. For more info on the states of
matter, click
here.