Editing Metal (section)

===Light metallic elements===
All elemental metals discovered before 1809 had relatively high densities; their heaviness was regarded as a distinguishing criterion. From 1809 onward, light metals such as sodium, potassium, and strontium were isolated. Their low densities challenged conventional wisdom as to the nature of metals. They behaved chemically as metals however, and were subsequently recognized as such.

Aluminium was discovered in 1824 but it was not until 1886 that an industrial large-scale production method was developed. Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal many uses at the time. During World War I, major governments demanded large shipments of aluminium for light and strong airframes.

While pure metallic titanium (99.9%) was first prepared in 1910 it was not used outside the laboratory until 1932. In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications as part of programs related to the Cold War. Starting in the early 1950s, titanium came into use in military aviation, particularly in high-performance jets, starting with aircraft such as the [[F-100 Super Sabre]] and [[Lockheed A-12]] and [[SR-71]].

Metallic scandium was produced for the first time in 1937. The first pound of 99% pure scandium metal was produced in 1960. Production of aluminium-scandium alloys began in 1971 following a U.S. patent. Aluminium-scandium alloys were also developed in the USSR.
<gallery widths="165" heights="165">
File:Na (Sodium).jpg|Chunks of sodium
File:Potassium-2.jpg|Potassium pearls under paraffin oil. Size of the largest pearl is 0.5&nbsp;cm.
File:Strontium destilled crystals.jpg|Strontium crystals
File:Aluminium-4.jpg|Aluminium chunk,<br />2.6&nbsp;grams, {{nowrap|1=1 x 2 cm}}
File:Titan-crystal bar.JPG|A bar of titanium crystals
File:Scandium sublimed dendritic and 1cm3 cube.jpg|Scandium, including a 1&nbsp;cm<sup>3</sup> cube
</gallery>