Each substance has a unique set of properties that depends on the kinds of atoms it has and how the atoms are connected, or bonded. Bonding is related to the electrons in an
atom, and there are different kinds of bonds. As a result, some substances can have the
same atoms but different bonds. Substances that are different but have the same atoms
are called allotropes. Allotropes have very different properties.
Diamond and graphite are well-known allotropes. Graphite is used in pencils for writing
and is sometimes called lead. Diamond is colorless and transparent, and is one of the
hardest substances known. Graphite is dark gray and soft. When we write, layers of
graphite easily transfer from the pencil to the paper. Although they're different, diamond
and graphite each only contain one kind of atom-carbon.
How do you think the bonds between carbon atoms might be different in diamond and
graphite? Use household materials to build physical models to help you develop your
ideas. Describe what you learned from your models. What other kinds of allotropes are
there? What kinds of properties and atomic bonds do they have?