Main Group Elements Definition

Know Which Elements Are in the Main Group

The main group elements are ones in columns below the Roman numerals.
The main group elements are ones in columns below the Roman numerals. Dorling Kindersley / Getty Images

In chemistry and physics, the main group elements are any of the chemical elements belonging to the s and p blocks of the periodic table. The s-block elements are group 1 (alkali metals) and group 2 (alkaline earth metals). The p-block elements are groups 13-18 (basic metals, metalloids, nonmetals, halogens, and noble gases). The s-block elements usually have one oxidation state (+1 for group 1 and +2 for group 2). The p-block elements may have more than one oxidation state, but when this happens, the most common oxidation states are separated by two units. Specific examples of main group elements include helium, lithium, boron, carbon, nitrogen, oxygen, fluorine, and neon.

Significance of the Main Group Elements

The main group elements, along with a few light transition metals, are the most abundant elements in the universe, solar system, and on Earth. For this reason, main group elements are sometimes known as representative elements.

Elements That Aren't in the Main Group

Traditionally, the d-block elements have not been considered to be main group elements. In other words, the transition metals in the middle of the periodic table and the lanthanides and actinides below the main body of the table are not main group elements. Some scientists do not include hydrogen as a main group element.

Some scientists believe zinc, cadmium, and mercury should be included as main group elements. Others believe group 3 elements should be added to the group. Arguments may be made for including the lanthanides and actinides, based on their oxidation states.