Group 1 Elements: Alkali Metals

Group 1 of the periodic table consists of six elements — lithium, sodium, potassium, rubidium, caesium and francium — together called the alkali metals. Moving down the group, atomic number rises steadily and with it comes a set of smooth, predictable trends in physical and chemical behaviour: atomic size increases, ionization enthalpy falls, reactivity climbs, and melting/boiling points drop. Because every member has just one electron beyond a closed noble-gas core, the group behaves almost as a single family whose properties can be read off a smooth curve rather than worked out element by element.

The sections below work through this family systematically — electronic configuration, atomic/ionic size, ionization enthalpy, hydration enthalpy, physical appearance and, finally, chemical reactivity — before turning to their compounds.