What are the vertical columns called on the periodic table?

The periodic table is a grid of all known chemical elements that exist. They are arranged in rows and columns in order of their atomic numbers. Similar atomic structures and properties are grouped together.

The vertical columns in the periodic table are called groups. There are 18 numbered groups in the periodic table, and the f-block columns are not numbered (between groups 3 and 4).

Elements contained within the same group have something in common. They have similar chemical properties because each group has the same number of electrons in the outer orbital. The outer electrons are called valence electrons.

An example would be alkali metals with one valence electron like lithium (Li) and potassium (K). Their actions are similar because they are very active, are not found free in nature by themselves (you typically find them as compounds) and react violently with water.