SiliconSilicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form.
SicilySicily (Sicilia siˈtʃiːlja; Sicilia sɪˈ(t)ʃiːlja) is the largest and most populous island in the Mediterranean Sea and one of the 20 regions of Italy with the Strait of Messina dividing it from the region of Calabria in Southern Italy. It is one of the five Italian autonomous regions and is officially referred to as Regione Siciliana. The region has 4.8 million inhabitants. Its capital city is Palermo. Sicily is in the central Mediterranean Sea, south of the Italian Peninsula in continental Europe, from which it is separated by the narrow Strait of Messina.
BrazilBrazil (Brasil; bɾaˈziw), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in South America and in Latin America. Brazil is the world's fifth-largest country by area and the seventh most populous. Its capital is Brasília, and its most populous city is São Paulo. The federation is composed of the union of the 26 states and the Federal District. It is the only country in the Americas to have Portuguese as an official language.
Conchoidal fractureConchoidal fracture describes the way that brittle materials break or fracture when they do not follow any natural planes of separation. Mindat.org defines conchoidal fracture as follows: "a fracture with smooth, curved surfaces, typically slightly concave, showing concentric undulations resembling the lines of growth of a shell". Materials that break in this way include quartz, chert, flint, quartzite, jasper, and other fine-grained or amorphous materials with a composition of pure silica, such as obsidian and window glass, as well as a few metals, such as solid gallium.
SilicosisSilicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silicosis (particularly the acute form) is characterized by shortness of breath, cough, fever, and cyanosis (bluish skin). It may often be misdiagnosed as pulmonary edema (fluid in the lungs), pneumonia, or tuberculosis. Using workplace controls, silicosis is almost always a preventable disease.
DiamondDiamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools.
