Groups on the periodic table are the vertical columns. There are 18 numbered groups in the modern IUPAC system, labeled 1 through 18, with many groups also having traditional names (for example, group 1 is the alkali metals, group 2 the alkaline earth metals, group 17 the halogens, and group 18 the noble gases). The f-block elements (lanthanoids and actinoids) sit between groups 3 and 4 and are not assigned numbers in the main table, while the d-block (transition metals) spans groups 3–12 and sits to the right of the s-block. Key points
- Groups share similar chemistry because elements in the same group have the same number of valence electrons, leading to similar bonding and oxidation behavior. This is why elements in a group often exhibit comparable reactivity and common oxidation states.
- The 18-group system is organized across the s-, p-, and d-blocks:
- Groups 1–2: s-block (alkali and alkaline earth metals)
* Groups 3–12: d-block (transition metals)
* Groups 13–18: p-block (metals, metalloids, and nonmetals, including the noble gases in group 18)
- The position within a group trends down the column generally show increasing atomic size and decreasing ionization energy, while electronegativity tends to decrease down a group for main-group elements. There are notable exceptions among the heavier elements due to relativistic effects and shielding.
If you’d like, I can tailor this to a specific group (for example, describe the alkali metals in group 1 or the halogens in group 17) and summarize typical properties, common oxidation states, and representative elements.
