The s-block metals are valuable for an enormous variety of applications, with few trends readily apparent; but their propensity for burning in air with vividly-coloured flames does make several members of the series of use in fireworks and flares. Potassium, magnesium and strontium are used for this purpose, strontium, for example, giving a brilliant red colour.
Potassium and magnesium are also used in the manufacture of explosives, and both rubidium and caesium are used in the making of photoelectric cells. The reactivity of these last two elements is exploited in their role as getters; both are used to remove traces of oxygen from vacuum tubes.
Radioactive isotopes of the elements are used in the detection and treatment of cancer. Rubidium, which gathers in diseased but not in normal tissue, is employed in the locating of brain tumours; and strontium is used in the detection of bone cancer.
Both lithium chloride and calcium chloride absorb water from the atmosphere, and are used as drying agents.
