| Everything in our
universe is composed of matter. Matter is made up of smaller particles
called molecules. Molecules are made up of atoms.
Atoms are the smallest particles that we are
able to break matter into. Atoms, in turn are made up of even smaller
particles: Neutrons, Protons and Electrons. However, all atoms are not the
same - atoms often differ from other atoms because of the number of protons
they have located in their nucleus. The different types of atoms are called
elements, or chemical elements. Currently, we have identified 109
elements. As we said before, elements can combine to form molecules. A
molecule contains two or more atoms. Elements can also combine to form
compounds. Compounds are a type of molecule that contains two or more
different elements.
So, all compounds are molecules but not all
molecules are compounds.
States of Matter
Matter exists in four basic states: solid, liquid, gas and plasma. Plasma
is a state of matter that does not commonly exist, so solid, liquid and gas
are the states of matter that are most commonly discussed.
The states of matter differ from each other
because of the amount that the molecules of matter move; Molecules in a
solid move very little, molecules in a liquid move very easily, and
molecules in a gas move very very quickly. So what causes the speed of the
molecules to change? Energy! Adding energy to a molecules makes molecules
move faster, while taking energy away makes molecules move more slowly.
Energy is most commonly added in the form of heat. For example, heating ice
adds energy to the ice and makes the molecules move more quickly and
freely. As a result, the molecules separate from each other and the matter
becomes liquid. Continuing to add heat after the ice has changed to water
makes the molecules move even more quickly, as in boiling water until it
changes into steam. |
