Bromine is quite reactive. Its reactivity is between chlorine, which is more reactive, and iodine, which is less reactive. It reacts with metals and nonmetals. Phosphorus reacts violently with bromine. Aluminum reacts in a similar way. It can bleach things like chlorine. It reacts better in the light. It dissolves a little in water. Hot water makes it disproportionate into hydrobromic acid and hypobromous acid. Bromine can form compounds with substances such as sodium to form sodium bromide.
Bromine forms compounds in many oxidation states: –1, +1, +3, +5, and (sometimes) +7. –1 is the most common. It is found as bromide. Bromides are not reactive. They are colorless solids that dissolve in water easily. Covalent bromides can be liquids or gases. The other compounds are all strong oxidizing agents. Their chlorine cousins are more common. +1 has the hypobromites, which are unstable. +3 has the bromites. Bromine dioxide is the only common bromine compound found in the +4 oxidation state. +5 has the bromates, which are more common than all the other ones except the bromides. Bromates are strong oxidizing agents and are sometimes added to flour. +7 has the perbromates. Perbromates are very unstable.
Bromine is found as bromide in the ocean and in brine pools. The Dead Sea has a lot of bromide in it. Bromine is not an important part of our body, unlike its relatives chlorine and iodine.
Bromine is made by bubbling chlorine gas through a solution of a bromide. The bromide is oxidized to bromine, while the chlorine is reduced to chloride.
It is mainly used to make organobromine compounds, organic compounds with bromine in them. Organobromines are used to put out fires. They used to be added to gasoline. Some were used as pesticides. Some inorganic bromides were used as sedatives. Bromine can also be used as a disinfectant. Silver bromide is used in film.
Bromine is toxic and corrosive to skin. Bromine gas is irritating when it is breathed in, too. Bromine can react violently with many things.
Fluorine
Fluorine (symbol F) is a chemical element that is very poisonous. Its atomic number (which is the number of protons in it) is 9, and its atomic mass is 19. It is part of the Group 7 (halogens) on the periodic table of elements.
Fluorine is a light yellow diatomic gas. It is very reactive gas, which exists as diatomic molecules. It is actually the most reactive element. Fluorine has a very high attraction for electrons, because it is missing one. This makes it the most powerful oxidizing agent. It can rip electrons from water (making oxygen) and ignite propane on contact. It does not need a spark. Metals can catch on fire when placed in a stream of fluorine. After it is reduced by reacting with other things, it forms the stable fluoride ion. Fluorine is very poisonous. Fluorine bonds very strongly with carbon. It can react with the unreactive noble gases. It explodes when mixed with hydrogen. The melting point of fluorine is -363.33°F (-219.62°C), the boiling point is -306.62°F (-188.12°C).
Chemical compounds containing fluorine ions are called fluorides. Fluorine only exists in one oxidation state: -1.
Fluorine is not found as an element on the earth; it is much too reactive. Several fluorides are found in the earth, though. When calcium phosphate is reacted with sulfuric acid to make phosphoric acid, some hydrofluoric acid is produced. Also, fluorite can be reacted with sulfuric acid to make hydrofluoric acid. Fluorite naturally occurs on the earths' crust in rocks, coal and clay.
Fluorine is normally made by electrolysis. Hydrogen fluoride is dissolved in potassium fluoride. This mixture is melted and an electric current is passed through it. This is electrolysis. Hydrogen is produced at one side and fluorine at the other side. If the sides are not separated, the cell may explode.
Someone made fluorine in 1986 without using electrolysis. They produced manganese(IV) fluoride by using various chemical compounds, which released fluorine gas.
Fluorine is used to enrich uranium for nuclear weapons. It is also used to make sulfur hexafluoride. Sulfur hexafluoride is used to propel stuff out of an aerosol can. It is also used to make integrated circuits. Fluorine compounds have many uses. Fluoride ions are in fluorine compounds. Fluoride ions can be in toothpaste. Some are used in nonstick coatings. Freons contain fluorine.
Fluorine as an element is extremely reactive and toxic. It can react with almost everything, even glass. Fluorine is also poisonous.
Fluoride ions are somewhat toxic. If too much toothpaste containing fluoride is eaten then fluoride poisoning may occur. Fluoride is not reactive, though.
Iodine
Iodine is a chemical element. Its atomic number (which is the number of protons in it) is 53, and its atomic mass (the number of protons plus neutrons) is 127. It is part of the Group 7 (halogens) on the periodic table of elements and its electronic configuration is 2,8,8,18,17. It is a nonmetal.
Iodine is a dark purple-black solid. It is also a nonmetal and a halogen. It sublimes when heated to make a bright purple vapor. This vapor is very irritating, although colorful. Iodine does not dissolve in water, but it does dissolve in a solution of an iodide in water. It dissolves easily in organic solvents.
Iodine is at the bottom of the halogens and is the least reactive of the halogens. Iodine is an oxidizing agent, though not as strong as bromine or chlorine. It can become the colorless iodide ion if another atom or molecule gives an iodine atom one of its electrons. This is called reduction. Iodine reacts with hydrogen sulfide or hydrazine to make hydriodic acid. Iodine dissolves in oleum to make a bright blue solution of I and sulfur dioxide. This cation is also made when iodine reacts with antimony pentafluoride.
Iodine reacts with bases to make hypoiodite and iodide. The hypoiodite disproportionates to iodate and iodide. Iodine reacts with nitric acid and chlorates to make iodates, too. Iodine reacts violently with some metals like aluminium to make large amounts of heat and toxic vapors.
Iodine forms chemical compounds in several oxidation states: -1, +1, +3, +5, and +7. This is typical of the halogens except for fluorine. -1 compounds as iodides are the most common. Most organic iodine compounds are in the -1 oxidation state. Most iodides are colorless or reddish-yellow and are weak reducing agents. +1 and +3 compounds are quite rare. They are both oxidizing agents. +1 compounds are found as iodine monochloride and hypoiodites. +3 compounds are found as iodine trichloride or iodine trifluoride. +5 compounds are found as iodates and iodic acid. Iodine pentafluoride and iodine pentoxide are iodine compounds in the +5 state. +5 and +7 compounds are all strong oxidizing agents. +7 compounds are normally found as periodates and periodic acid. Iodine heptafluoride is also in the +7 oxidation state.
Potassium iodide is one of the most common iodides. Iodides are normally colorless but turn yellow after being in air because the iodide is oxidized to iodine. Iodides react with acidified manganese dioxide or chlorine to make iodine. Iodine monochloride is a red or brown liquid. Iodine trichloride, as well as iodine trifluoride, are yellow solids. Iodates like potassium iodate are colorless solids similar to chlorates. Iodic acid is the only stable oxidizing halogen acid. Chloric acid, by comparison, is very unstable and dangerous. Iodine pentoxide is a white solid, and iodine pentafluoride is a yellowish liquid. Periodates, like sodium periodate, are colorless solids similar to perchlorates, although weaker oxidizing agents. They decompose to iodates when they are heated. Periodic acid is not as stable as iodic acid. Iodine heptafluoride is the only iodine(VII) compound.