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Hydrofluorocarbons (HFCs), organic compounds that contain fluorine and hydrogen atoms, are the most common type of organofluorine compounds. They are commonly used in air conditioning and as refrigerants [ 5 ] in place of the older chlorofluorocarbons such as R-12 and hydrochlorofluorocarbons such as R-21 .
The rest of the unaccounted carbon bonds are occupied by chlorine atoms. The value of this equation is always a three figure number. An easy example is that of CFC-12, which gives: 90+12=102 -> 1 carbon, 0 hydrogens, 2 fluorine atoms, and hence 2 chlorine atoms resulting in CCl 2 F 2. The main advantage of this method of deducing the molecular ...
Fluorine-19 nuclear magnetic resonance spectroscopy (fluorine NMR or 19 F NMR) is an analytical technique used to detect and identify fluorine-containing compounds. 19 F is an important nucleus for NMR spectroscopy because of its receptivity and large chemical shift dispersion, which is greater than that for proton nuclear magnetic resonance ...
The covalent radius of fluorine of about 71 picometers found in F 2 molecules is significantly larger than that in other compounds because of this weak bonding between the two fluorine atoms. [9] This is a result of the relatively large electron and internuclear repulsions, combined with a relatively small overlap of bonding orbitals arising ...
Fluorine is a chemical element; it has symbol F and atomic number 9. It is the lightest halogen [note 1] and exists at standard conditions as pale yellow diatomic gas. Fluorine is extremely reactive as it reacts with all other elements except for the light inert gases. It is highly toxic.
Two-way indicator species analysis (TWINSPAN) is a Fortran-based statistical analysis method described in 1979 by Mark O. Hill. [1] It is widely used in ecological research. [ 2 ] As of 1997, it was the only widespread standardized method to identify indicator plants.
For example, F/C=C/F (see depiction) is one representation of trans-1,2-difluoroethylene, in which the fluorine atoms are on opposite sides of the double bond (as shown in the figure), whereas F/C=C\F (see depiction) is one possible representation of cis-1,2-difluoroethylene, in which the fluorines are on the same side of the double bond.
An air quality index (AQI) is an indicator developed by government agencies [1] to communicate to the public how polluted the air currently is or how polluted it is forecast to become. [ 2 ] [ 3 ] As air pollution levels rise, so does the AQI, along with the associated public health risk.