Alkali Metals

Alkali metals are group 1 elements, including lithium, sodium, potassium, rubidium, cesium, and francium. Francium is radioactive and has no stable isotopes.

All alkali metals are unusually soft and share metallic properties, such as high electrical and thermal conductivity. Moving down the group, the mass and atomic radius increase, while the melting points and first ionization energies decrease. Density generally increases down the group, except for potassium, because the increase in atomic mass is greater than the increase in atomic volume.

The electron configuration of these elements implies that the valence shell has only one electron.

Their low ionization energies indicate that alkali metals readily lose electrons to become cations with a noble gas configuration. This also explains why alkali metals are excellent reducing agents, with lithium being the least reactive and cesium the most.

Alkali metals react vigorously with nonmetals, such as halogens, to form salts. The reaction of sodium metal with chlorine gas is highly exothermic and releases sparks and heat. The intensity of the reaction increases down the group as the ionization energies of the alkali metals decrease.

Alkali