Halomethane compounds are molecules of methane (CH₄) with one or more of the hydrogen atoms replaced with halogen atoms. The halogens are found in group 17 of the periodic table of the elements. Forming covalent bonds, these compounds are generally stable. The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number Hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1, s Density, Hardness 0. ... General Name, Symbol, Number Hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1, s Density, Hardness 0. ... The halogens are a chemical series. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ...

While these are all considered to be human-made compounds, they may appear inadvertently via natural processes in the environment through the introduction of other non-natural industrial materials. An example is the creation of carbon tetrachloride in small (yet slightly dangerous) quantities when carbon bearing materials are present in drinking water disinfected with chlorine gas. As carbon tetrachloride is believed to be carcinogenic (cancer causing), chlorine gas is being replaced with chloramine for this use. In pathology, a carcinogen is any substance or agent that promotes cancer. ... Chloramine (monochloramine) is a toxic substance (NH2Cl) created by the chemical reaction of ammonia and sodium hypochlorite (chlorine bleach) under alkaline conditions. ...

Some of these compounds, while normally inert, become active when exposed to ultraviolet light found at high altitudes and can destroy the earth's protective ozone layer. The most damaging ones are being phased out of use as industrial materials. Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. ... The ozone layer is that part of the Earths stratosphere which contains relatively high concentrations of ozone (O3). ...

While most of these compounds are considered inert under normal conditions, some are irritants. At high temperatures there may be toxic byproducts produced.

Combinations of halogens with short carbon chains form related compounds such as haloethanes, halopropanes, halobutalines, etc, typically useful as refrigerants, fire suppressing gases, solvents, and as starting points for stable and useful plastics such as Teflon. Some are in crystal form.

Freon is a trade name for a group of chlorofluorocarbons used primarily as refrigerants. The word Freon® is a registered trademark belonging to E.I. du Pont de Nemours & Company. Freon is a trade name for a group of chlorofluorocarbons used primarily as a refrigerant. ... For other uses, see CFC (disambiguation). ... Refrigeration (from the Latin frigus, frost) is generally the cooling of a body by the transfer of a portion of its heat away from it. ... This article is about the DuPont company. ...

The naturally occurring halogen elements forming halomethanes are:

• Fluorine, being the most active element forms extremely stable compounds with carbon.
  • Fluorometane (methyl fluoride, CH_3/F)
  • Difluoromethane (CH₂F₂)
  • Trifluoromethane (fluoroform, CHF₃), Freon-23
  • Carbon tetrafluoride (CF₄), a low boiling point gas used in refrigeration. Known as Freon-14, refrigerant 14, R14 and other names

• Chlorine
  • Dichloromethane (DCM, methylene chloride, CH₂Cl₂) is a widely used organic solvent mainly used as a solvent for industrial processes, stripping paint, and degreasing parts. However, it has other uses as varied as decaffeinating coffee and preparing flavor extracts.
  • Chloroform (trichloromethane, CHCl₃) used to be used as an anesthetic but fell out of use due to its toxicity. It finds use today as an industrial solvent and in the production of dyes and pesticides.
  • Carbon tetrachloride (CCl₄) binds four chlorine to each carbon, forming a non-flammable liquid of low boiling point. Once used as a cleaning fluid and in fire extinguishers, it is now known to be extremely toxic and carcinogenic.

• Bromine
  • Carbon tetrabromide (CBr₄)

• Iodine
  • Carbon tetraiodide (CCI₄)

• Combinations - substitutions of fluorine, chlorine and bromine for 3 or 4 of the hydrogens yields various refrigerant or fire suppressing gases.
  • Chlorodifluoromethane (CHClF₂), Freon-22
  • Chlorotrifluoromethane (CClF₃), Freon-13
  • Trichlorofluoromethane (CCl₃F), Freon-11
  • Dibromodifluoromethane (CBr₂F₂)
  • Dichlorodifluoromethane (CCl₂F₂), Freon-12
  • Dichlorofluoromethane (CHCl_2F), Freon-21
  • Diflorodibromomethane (CF₂Br₂)

General Name, Symbol, Number Fluorine, F, 9 Series Halogens Group, Period, Block 17 (VIIA), 2, p Density, Hardness 1. ... Difluoromethane is an organic compound of the di-halogenoalkane variety. ... General Name, Symbol, Number chlorine, Cl, 17 Series halogens Group, Period, Block 17 (VIIA), 3, p Density, Hardness 3. ... Dichloromethane or Methylene chloride is a chemical compound widely used as a solvent for organic materials. ... Chloroform (also known as trichloromethane and methyl trichloride) is a chemical compound with formula CHCl3. ... Anesthesia (AE), also anaesthesia (BE), is the process of blocking the perception of pain and other sensations. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ... An airplane spreading pesticide. ... Tetrachloromethane (carbon tetrachloride)CCl4 is a synthetic chemical compound formerly widely used in fire extinguishers and refrigeration, but now largely abandoned due to its toxicity. ... General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79. ... General Name, Symbol, Number iodine, I, 53 Series halogens Group, Period, Block 17 (VIIA), 5, p Density, Hardness 4940 kg/m3, no data Appearance violet-dark grey, lustrous Atomic properties Atomic weight 126. ... R-11, or trichlorofluoromethane, was the first widely used refrigerant. ... Dichlorodifluoromethane, or R-12, is a halomethane used as a refrigerant and propellant in aerosol sprays until its manufacture was discontinued due to concerns about damage to the ozone layer. ...

External links

• http://www.calstand.com/GasConversionTable.html