What is Matter?

Explain what matter is.
Defi nitions are useful in all areas of knowledge; they provide a common vocabulary
for both presentations to students and discussions between professionals. You will be
expected to learn a number of defi nitions as you study chemistry, and the fi rst one is
a defi nition of matter. Earlier, we said that matter is the substance of everything. That
isn’t very scientifi c, even though we think we know what it means. If you stop reading
for a moment and look around, you will see a number of objects that might include
people, potted plants, walls, furniture, books, windows, and a TV set or radio. The objects
you see have at least two things in common: Each one has mass, and each one
occupies space. These two common characteristics provide the basis for the scientifi c
defi nition of matter. Matter is anything that has mass and occupies space. You probably
understand what is meant by an object occupying space, especially if you have tried to
occupy the same space as some other object. The resulting physical bruises leave a lasting
mental impression.
You might not understand the meaning of the term mass quite as well, but it can also
be illustrated painfully. Imagine walking into a very dimly lit room and being able to just
barely see two large objects of equal size on the fl oor. You know that one is a bowling ball
and the other is an infl ated plastic ball, but you can’t visually identify which is which.
However, a hard kick delivered to either object easily allows you to identify each one. The
bowling ball resists being moved much more strongly than does the infl ated ball. Resistance
to movement depends on the amount of matter in an object, and mass is an actual
measurement of the amount of matter present.
The term weight is probably more familiar to you than mass, but the two are related.
All objects are attracted to each other by gravity, and the greater their mass, the stronger
the attraction between them. The weight of an object on Earth is a measurement of the
gravitational force pulling the object toward Earth. An object with twice the mass of a
second object is attracted with twice the force, and therefore has twice the weight of the
second object. The mass of an object is constant no matter where it is located (even if it
is in a weightless condition in outer space). However, the weight of an object depends on the strength of the gravitational attraction to which it is subjected. For example, a rock
that weighs 16 pounds on Earth would weigh about 2.7 pounds on the moon because the
gravitational attraction is only about one-sixth that of Earth. However, the rock contains
the same amount of matter and thus has the same mass whether it is located on Earth or
on the moon.
Despite the difference in meaning between mass and weight, the determination of mass
is commonly called “weighing.” We will follow that practice in this book, but we will use
the correct term mass when referring to an amount of matter


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