materiały: Nonmetal

Evidence: 100 • authority: 72

In the context of the periodic table, a nonmetal is a chemical element that mostly lacks distinctive metallic properties. Physically, nonmetals range from colorless gases such as hydrogen to lustrous crystalline solids such as iodine. They are usually less dense than metals and are often poor conductors of heat and electricity. Chemically, they have moderate to very high electronegativity—a tendency to attract electrons in a chemical bond—and their oxides tend to be acidic. Seventeen elements are widely recognized as nonmetals. Additionally, some or all of six borderline elements (metalloids) are sometimes counted as nonmetals. The two lightest nonmetals, hydrogen and helium, together make…

Evidence: 45 • authority: 72

The word metalloid comes from the Latin metallum ("metal") and the Greek oeidḗs ("resembling in form or appearance"). However, there is no standard definition of a metalloid and no complete agreement on which elements are metalloids. Despite the lack of specificity, the term remains in use in the literature. The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. Five elements are less frequently so classified: carbon, aluminium, selenium, polonium and astatine. On a standard periodic table, all eleven elements are in a diagonal region of the p-block extending from boron at the upper left to astatine at lower right. Some periodic tables include…

Evidence: 35 • authority: 80

Ornaments in the Late 18th century and 19th

Evidence: 33 • authority: 72

Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's ab…

Evidence: — • authority: 72

Lead ( ) is a chemical element with the symbol Pb (from Latin plumbum) and has the atomic number 82. It is a heavy metal, meaning it is denser than most common materials. Lead is malleable and soft, meaning it can be shaped into different shapes and lead has a relatively low melting point. When freshly cut or melted, it appears shiny silvery with a bluish tint, but tarnishes to dull gray on exposure to air. Lead has the highest atomic number of any stable element, and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead is a relatively un-reactive post-transition metal. Its weak metallic character is shown by its amphoteric behavior: lead and lead oxid…

Evidence: — • authority: 72

Tinctures are the colours, metals, and furs used in heraldry. There are nine tinctures in common use: two metals, five colours, and two furs. The metals are or (gold or yellow) and argent (silver or white); the colours gules (red), azure (blue), vert (green), sable (black), and purpure (purple); and the furs ermine, which is derived from the winter fur of a stoat, and vair, which is derived from the fur of a red squirrel. The use of other tinctures varies depending on the time period and heraldic tradition in question. Where the tinctures are not depicted in full colour, they may be represented using one of several systems of hatching, in which each tincture is assigned a distinct pattern;…

Evidence: — • authority: 72

Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic, and chemical properties, but copper typically has the larger proportion, generally 2⁄3 copper and 1⁄3 zinc. In use since prehistoric times, it is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. Brass is similar to bronze, a copper alloy that contains tin instead of zinc. Both bronze and brass may include small amounts of a range of other elements, including arsenic, lead, phosphorus, aluminium, manganese, silicon, and (in marine brass) tin. Historically, the distinction between the two allo…

Evidence: — • authority: 72

Heavy metals is a controversial and ambiguous term for metallic elements with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context, and arguably, the term "heavy metal" should be avoided. A heavy metal may be defined on the basis of density, atomic number, or chemical behaviour. More specific definitions have been published, none of which has been widely accepted. The definitions surveyed in this article encompass up to 96 of the 118 known chemical elements; only mercury, lead, and bismuth meet all of them. Despite this lack of agreement, the term (plural or singular) is widely used in…

Evidence: — • authority: 92

Searching for a Clue to Characterize a Crystalline Dinosaur's Eggshell of Baja California, Mexico.. This work presents a detailed structural and morphological analysis of different dinosaur eggshells such as Spheroolithus (sample 1, 2), lambeosaurinae, Prismatoolithus , and one unidentified ootaxon performed by high-resolution scanning electron microscopy (HRSEM). These ancient eggshells of Late Cretaceous dinosaurs were collected in the coastal area of El Rosario, Baja California in Mexico. Additionally, a thorough study was performed on the elements present in the samples by different techniques such as energy-dispersive spectroscopy (EDS), X-ray fluorescence (XRF), and X-ray photoelectro…