hovedgruppen

Hovedgruppen, in Norwegian chemical terminology, refers to the main group elements of the periodic table. The term is used to describe the elements located in groups 1, 2, and 13 through 18, i.e., the s- and p-block elements, and excludes the transition metals in groups 3 through 12. These elements share the characteristic that their outermost electrons occupy s and/or p orbitals, which influences their chemical properties and bonding behavior.

In contrast to the transition metals, which have partially filled d orbitals and often variable oxidation states, the main group elements display trends largely governed by their valence electrons. Across a period, properties such as ionization energy, electronegativity, and electron affinity show systematic changes, while within a group they exhibit reactivity patterns tied to their valence electron configuration. For example, alkali metals (group 1) are highly reactive metals, alkaline earth metals (group 2) are reactive metals, the boron group (group 13) and carbon group (group 14) include metals and metalloids, the nitrogen group (group 15) and oxygen group (group 16) include nonmetals and metalloids, halogens (group 17) are highly reactive nonmetals, and noble gases (group 18) are largely inert.

Hydrogen is often discussed alongside the main group elements due to similarities in electronic structure, though its placement can vary in different periodic tables. The concept of hovedgruppen helps organize the periodic table, teaching about electron configurations, periodicity, and bonding while highlighting distinctions from the transition metals.