Final answer:
The periodic table is said to be periodic because the properties of the elements repeat themselves according to a regular repeating pattern.
Step-by-step explanation:
The periodic table is said to be periodic because the properties of the elements repeat themselves according to a regular repeating pattern. This means that elements with similar properties are grouped together in the same vertical column, which is called a group or family. The periodic table also arranges the elements in increasing order of their atomic numbers, which is the number of protons in the nucleus of an atom.