Malleability

This page covers one of the intensive properties of matter: Malleability

By: Kyle Williams

The Main Idea

A Property of Matter

Properties of matter can be broken down into two distinct categories: physical and chemical. The physical category can also be broken down in a similar manner, consisting of intensive and extensive properties. A physical property is one that can be determined without changing the identity of the substance, and intensive properties can be determined regardless of the amount of matter of the substance present.

What is Malleability?

Malleability is one such intensive property of matter. Malleability is the ability for something, generally metals, to be molded or deformed into another shape. Often considered to simply be the ability for a metal to be hammered into thin sheets, malleability is actually a material's ability to deform under pressure of a force pushing on it, in other words, a compressive force. It is similar to ductility which is the ability of a material to stretch under a force that pulls and creates tension, or, in other words, a tensile stress.

How Does it Work?

Malleability in metals is due to metallic bonds which are characterized by a mobile "electron sea". The electrons are able to move around and allow the metal atoms to adjust back and forth, past other atoms if a force is applied to them. The amount the atoms move is dependent upon two key factors: the temperature and the strength of the metallic bonds. Having weak metallic bonds means that there is less energy required to move the relative positions of the atoms and therefore means the material will have a higher malleability. Temperature affects the malleability of a material by regulating the crystalline structure of the atoms. In most metals, the heat makes the structure of the atoms more regular which softens the metal and makes it more malleable.

Examples

Common Uses

While malleability can be considered to some extent with everything you see everyday, one of the most common everyday uses of malleability is with aluminum foil. Whether for a science project or for leftovers from dinner, the ability to crumple up or change the shape of aluminum foil is quite convenient. Pottery and horseshoes are also common examples of malleability put to work.

Industrial Applications

The property of malleability is utilized in industrial applications through processes such as forging, drop-stamping, and hot-rolling. These and many other processes allow different metals to be worked and formed into all sorts of useful items. Steel-girder bridges, one of the most common types of modern bridges used, are an interesting application of this property. The steel grid helps support the concrete deck that serves as the walkway or roadway surface. The supporting structure of the bridge consists mainly of the steel holding up the deck. Without malleability, the beams used for these types of bridges wouldn't be able to be forged and stamped, nor would they be able to withstand the compression that the load on the bridge itself causes.

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History

Derived from the Medieval Latin word, malleābilis (almost directly meaning "hammer-able"), malleability has been understood and utilized for centuries for a variety of things. Such uses range from the molding of clay for pottery to the forging of swords and armor in Medieval times, and even to the production of steel beams used in the construction of modern bridges. The modern era of chemistry and physics, however, has allowed a more controlled use of this intensive property of matter in industrial applications.

See also

Ductility and Conductivity

External links and Further Reading

http://metals.about.com/od/metallurgy/a/Malleability.htm

http://www.boeingconsult.com/tafe/structures/struct1/Stress-strain/stress-strain.HTM

References

http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter

http://study.com/academy/lesson/malleability-in-chemistry-definition-examples-quiz.html

https://en.wikipedia.org/wiki/Girder_bridge