Cr Chroom 24 51.9961 6 4 d 24 1857.0 2672.0 [Ar] 3d5 4s1 2 8 13 1 7.19 0.014% Silver Cubic: Body centered 1.7 1.65 {"1":"652.9","2":"1590.6","3":"2987","4":"4743","5":"6702","6":"8744.9","7":"15455","8":"17820","9":"20190","10":"23580","11":"26130","12":"28750","13":"34230","14":"37066","15":"97510","16":"105800","17":"114300","18":"125300","19":"134700","20":"144300","21":"157700","22":"166090","23":"721870","24":"761733"} 653 64.3 127 +3,2,6 1.3 7.23 20.0 339.5 0.449 93.7 393.K 0 Solid, Antiferromagnetic, Conductor, TransitionMetal, Metal, Stable, Natural KROH-mi-em Very hard, crystalline, steel-gray metal. The pure metal has a blue-white color. It is hard, brittle and corrsion-resistant at normal temperatures. Used to make stainless steel. It gives the color to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology. Chromite [Fe,Mg(CrO4)] is its most important mineral. Produced commercially by heating its ore in the presence of silicon or aluminium. lzRb4zmGvNU Chromium

In 1800, Sir Humphry Davy thought silica to be a compound and not an element; but in 1811, Gay Lussac and Louis Jacques Thénard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride.

In 1824 Jöns Jakob Berzelius prepared amorphous silicon by the same general method.

Henri Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element. From the Latin word silex, silicis, flint 24 1797 Louis-Nicholas Vauquelin France From the Greek word "chroma" meaning "colour", named for the many coloured compounds known for chromium.

If breathed in as a fine silica/silicate dust, it may cause chronic respiratory problems

Silicon also has the unusual property that it expands as it freezes

In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc.

Silica, as sand, is a principal ingredient of glass.

Silicon chips are the basis of modern electronic and computing.

Silicon carbide, more commonly called carborundum is used in abrasives.