Element groups

Science

Definition

Element groups are the vertical columns on the periodic table, containing elements with similar chemical properties due to having the same number of valence electrons. Major groups include alkali metals, alkaline earth metals, halogens, and noble gases.

Examples

  • Group 1 alkali metals (Li, Na, K) are highly reactive and all have one valence electron
  • Group 17 halogens (F, Cl, Br, I) need one electron to complete their octet and are very reactive nonmetals
  • Group 18 noble gases (He, Ne, Ar) have full valence shells and are generally inert
Key Fact

Group number (for main-group elements) = number of valence electrons. Group 1 = 1, Group 2 = 2, Groups 13-18 = 3-8.

Related Terms

Periodic trends Electron configuration Metals nonmetals metalloids Electronegativity

Study This Concept

Practice element groups with free review games in these units:

Chemistry Unit 2: The Periodic Table