Cobalt(II) fluoride Cobalt(II) fluoride Cobalt(II) fluoride is a chemical compound with the formula (CoF). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (T=37.7 K) The formula is given for both the red tetragonal crystal, (CoF), and the tetrahydrate red orthogonal crystal, (CoF·4HO). CoF is used in oxygen-sensitive fields, namely metal production. In low concentrations, it has public health uses. CoF is sparingly soluble in water. The compound can be dissolved in warm mineral acid, and will decompose in boiling water. Yet the hydrate is water-soluble, especially the di-hydrate CoF·2H O and tri-hydrate CoF·3HO forms of the compound.
Chemical element For example, the formula for heavy water may be written DO instead of HO. Only about 4% of the total mass of the universe is made of atoms or ions, and thus represented by chemical elements. This fraction is about 15% of the total matter, with the remainder of the matter (85%) being dark matter. The nature of dark matter is unknown, but it is not composed of atoms of chemical elements because it contains no protons, neutrons, or electrons. (The remaining non-matter part of the mass of the universe is composed of the even more mysterious dark energy). The