What do the groups in the periodic table represent?

The groups in the periodic table correspond to vertical columns, and they represent elements that share similar chemical properties. This occurs because elements within the same group have the same number of valence electrons, which are the electrons involved in chemical bonding. For instance, all alkali metals (found in Group 1) have one valence electron, making them highly reactive and results in similar chemical behavior. Similarly, Group 17 elements, known as halogens, each have seven valence electrons, giving them a tendency to form salts and similar compounds.

The focus on chemical properties in groups specifically demonstrates why understanding the periodic table's organization is vital for predicting how different elements will react chemically. Elements from other groups or periods may have different properties and reactions, highlighting how crucial it is to recognize the significance of groupings in the periodic table.