Alkali metal nitrate

[1] They are white, water-soluble salts with melting points ranging from 255 °C (LiNO3) to 414 °C (CsNO3) on a relatively narrow span of 159 °C [2] The melting point of the alkali metal nitrates tends to increase from 255 °C to 414 °C (with an anomaly for rubidium being not properly aligned in the series) as the atomic mass and the ionic radius (naked cation) of the alkaline metal increases, going down in the column.

Similarly, but not presented here in the table, the solubility of these salts in water also decreases with the atomic mass of the metal.

[1] Eutectic mixtures of alkali metal nitrates are used as molten salts.

[4] A minor use is for coloring the light emitted by fireworks:[5] In a general way, the emitted color progressively turns from the red to the violet in the visible spectrum of light when going down in the column of the alkaline metals in the periodic table of Mendeleev.

It corresponds to a decrease of the wavelength of the light emitted during the electrons de-excitation step in the atoms brought at high temperature.