Why are columns called families on the periodic table?

The reason is pretty simple elements in the same columns belong to the same family or group because they then to share similar chemical properties due to the fact that they have the same valence electron shell configuration . read more

In the periodic table of elements, there are seven horizontal rows of elements called periods. The vertical columns of elements are called groups, or families. (See also The Periodic Table: Metals, Nonmetals, and Metalloids.) Periods in the periodic table. In each period (horizontal row), the atomic numbers increase from left to right. read more