An understanding of periodic trends is important because the trends 1. can be used to convert non-useful elements to useful ones. 2. allow compounds to be broken into their elements. 3. relate to properties of elements and how they may react. 4. allow prediction of electron configurations and bond orders.

3. relate to properties of elements and how they may react. Periodic trends are specific patterns that are present in the periodic table that include size, electronic properties, melting point, electronegativity and metallic character. The trends exist due to the similar atomic structure of the elements within each group family.

The answer is celsius