Potassium fluoride is colorless cubic crystal or white powder,soluble in water, alkaline, insoluble in ethanol, easy to absorb moisture and irritation.At 42℃,KF?2H2O. water soluble 92g/100ml C=18 C is easy to form.The melting point is 858℃，the boiling point is 1502℃，the density is 2.48g/cm3。

Sodium fluoride is colorless and shiny crystal or white powder.Its specific gravity is 2.25,melting point is 993 degrees, boiling point is1695 °C.

Soluble in water, hydrofluoric acid, slightly soluble in alcohol. Aqueoussolution is weakly alkaline, soluble in hydrofluoric acid, and sodium fluoride.It can corrode glass. Poisonous!

Ammonium hydrogen fluoride is the crystallizationof the melting point 125 C boiling point 230 degree C density 1.5 white orcolourless clear inclined crystal system. The commodity is flaky and slightlyacidic. It is easily dissolved in water and decomposed in hot water, and thewater solution is strong acid.

Colorless solid or cubic crystals, slightly acidic,odorless, and bimodal compounds. It is soluble in water and insoluble inethanol.

?

The melting point is 239 °C, and the density is 2.?37g/cm3.

?

The solid adopts the fluorite structure and at high pressure the PbCl2 structure. In the vapor phase the BaF2 molecule is non-linear with an F-Ba-F angle of approximately 108°. This is an exception to VSEPR theory which would predict a linear structure. Ab initio calculations have been cited to propose that contributions from d orbitals in the shell below the valence shell are responsible. Another proposal is that polarisation of the electron core of the barium atom creates an approximately tetrahedral distribution of charge that interacts with the Ba-F bonds.

Magnesium fluoride is an inorganic compoundwith the formula MgF2. The compound is a white crystalline salt and is transparent over a wide range of wavelengths, with commercial uses in optics that are also used in space telescopes. It occurs naturally as the rare mineral sellaite.