Iron

This article is about iron the metal. For the tool called iron, see ironing.

A chunk of iron

Iron (Fe) is the most common metal on Earth. It is element 26, a transition metal in Group 8. Its symbol is Fe, from the Latin word for iron, ferrum. Its atomic number is 26 and its mass number is 55.85.

It is used a lot because it is very strong and cheap. Iron is the main thing used to make steel. As iron is magnetic, it can be used to make a magnet.

Properties

Physical properties

Iron is a grey, silvery metal. It is magnetic. It is very strong, which is why it is used. Pure iron is malleable, while steel (iron mixed with a little carbon) is stronger. The more carbon there is in the iron, the stronger it is, although too much carbon will make it brittle.

Chemical properties

Iron is quite reactive. It reacts with most acids like sulfuric acid. It makes ferrous sulfate when reacted with sulfuric acid. This reaction with sulfuric acid is used to clean metal.

Iron reacts with air and water to make rust. The rust flakes off, making more iron rust. Eventually, the whole piece of iron is rusted away. Other metals like aluminum do not rust away. Iron can be alloyed with chromium and carbon to produce stainless steel, which does not rust under normal conditions.

Iron powder can react with sulfur to make iron(II) sulfide, a hard black solid. Iron also reacts with the halogens to make iron(III) halides, like iron(III) chloride. Iron reacts with the hydrohalic acids to make iron(II) halides like iron(II) chloride.

Chemical compounds

Iron makes chemical compounds with other elements. Normally the other element oxidizes iron. Sometimes two electrons are taken and sometimes three. Compounds where iron has two electrons taken are called ferrous compounds. Compounds where iron has three electrons taken are called ferric compounds. Ferrous compounds have iron in its +2 oxidation state. Ferric compounds have iron in its +3 oxidation state. Iron compounds can be black, brown, yellow, green, or purple.

Ferrous compounds are weak reducing agents. Many of them are green or blue. The most common ferrous compound is ferrous sulfate.

Ferric compounds are oxidizing agents. Many of them are brown. The most common ferric compound is ferric oxide, the same thing as rust. One reason why iron rusts is because ferric oxide is an oxidizing agent. It oxidizes iron, rusting it even under paint. That is why if there is a small scratch in the paint, the whole thing can rust.

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  Iron(III) oxide

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  Iron(II) oxide

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  Iron(II) sulfate

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  Iron(III) chloride

Iron in the ground

Iron is hardly ever found in the earth. Sometimes rocks that fall from outer space have iron metal in them. Normally hematite is in the ground. The hematite is used to make iron metal.

Some iron is found in meat. Iron is also found in hemoglobin in blood. Not all blood has hemoglobin in it, though.

Making iron

Blast furnace

Iron is made in large factories called ironworks by reducing hematite with carbon (coke). This happens in large containers called blast furnaces. The blast furnace is filled with iron ore, coke and limestone. A very hot blast of air is blown in, where it burns up the coke. The extreme heat makes the carbon react with iron ore, taking off the oxygen from iron oxides, and making carbon dioxide. There is normally some sand in with the iron. The limestone, which is made of calcium carbonate, turns into calcium oxide and carbon dioxide when very hot. The calcium oxide reacts with the sand to make a liquid called a slag. This is drained, leaving the iron. The reaction will leave pure liquid iron on the bottom of the blast furnace, where it can be shaped and hardened after cooling down. Almost all ironworks are today part of steel mills, and almost all iron is further processed into steel.

There are many ways to work iron. Iron can be hardened by heating a piece of metal and splashing it into cold water. It can be softened by heating it and allowing it to slowly cool. It can also be stamped by a heavy press. It can be pulled into wires. It can be rolled to make sheet metal.

In the United States, much of the iron was taken from the ground in Minnesota and then sent by ship to Indiana and Michigan where it was made into steel.

Uses

As a metal

A bridge made out of iron

Iron is used more than any other metal. It is strong and cheap. It is used to make buildings, bridges, nails, screws, pipes, girders, and towers. Iron is magnetic, so it is used in many magnets.

Iron is used in bridges because it is very strong thats why its so hard to get out. It is also very easy to get to. There is a lot in the world so it is cheap.

There are different types of iron. Cast iron is iron made by the way described above in the article. It is hard and brittle. It is used to make things like storm drain covers, manhole covers, and engine blocks (the main part of an engine).

Steel is the most common form of iron. Steels come in several forms. Mild steel is steel with a little carbon. It is soft and easily bent, but it does not crack easily. It is used for nails and wires. Carbon steel is harder but more brittle. It is used in tools. There are other special types of steel. Stainless steel does not rust. Some other types of steel are very strong. Other types are very hard.

Wrought iron is easily shaped and used to make fences and chains.

Some iron is very pure. It just has iron in it. This iron is very soft and easily made into a magnet. It is made by electrolysis of iron(II) chloride solution. It is used in the core of an electromagnet.

As compounds

Iron compounds are used for several things. Iron(II) chloride is used to make water clean. Iron(III) chloride is also used. Iron(II) sulfate is used to reduce chromates in cement. Some iron compounds are used in vitamins.

Use in food

Our bodies need iron to help oxygen get to our muscles, because the molecule is at the heart of some essential macromolecules such as hemoglobin. Many cereals have some added iron (the element metal iron). It is added to cereal in the form of tiny metal filings. It is even possible to see the slivers sometimes by taking an extremely strong magnet and putting it into the box. The magnet will attract these pieces of iron. Eating these small metal shavings are not harmful to our body.

Iron is most available to the body when added to amino acids – iron in this form is ten to fifteen times more digestible than than it is as an element. Iron is also found in meat, for example steak. Iron provided by diet supplements is in the form of a chemical, such as a sulphate, which is cheap and is absorbed well. The body will not take up more iron than it needs, and it usually needs very little. The iron in red blood cells is recycled by a system which breaks down old cells. Loss of blood by injury or parasite infection may be more serious.

Safety

Iron is toxic when large amounts are swallowed. It can damage the body. When too many vitamins that have iron in them are eaten, people get sick. There are chemicals that doctors have that can react with iron and stop it from poisoning people.

Other pages

• Iron compounds