Block (periodic table)A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term seems to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-block, p-block, d-block, f-block and g-block. The block names (s, p, d, and f) are derived from the spectroscopic notation for the value of an electron's azimuthal quantum number: sharp (0), principal (1), diffuse (2), and fundamental (3).
ArsenicArsenic is a chemical element; it has the symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is notoriously toxic. It occurs naturally in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.
AntimonyChemical element with atomic number 51 (Sb)As↑Sb↓Bitin ← antimony → tellurium
PoloniumPolonium is a chemical element; it has symbol Po and atomic number 84. A rare and highly radioactive metal (although sometimes classified as a metalloid) with no stable isotopes, polonium is a chalcogen and chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbours in the periodic table: thallium, lead, and bismuth.
BoronBoron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride.
SiliconChemical element with atomic number 14 (Si)C↑Si↓Gealuminium ← silicon → phosphorus
GermaniumGermanium is a chemical element; it has the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid (sometimes considered a nonmetal) in the carbon group that is chemically similar to silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature. Because it seldom appears in high concentration, germanium was found comparatively late in the discovery of the elements.
TelluriumSe↑Te↓Poantimony ← tellurium → iodine
AstatineI ↑At↓Tspolonium ← astatine → radon
AluminiumB↑Al↓Gamagnesium ← aluminium → silicon
SeleniumS↑Se↓Tearsenic ← selenium → bromine
CarbonChemical element with atomic number 6 (C)–↑C↓Siboron ← carbon → nitrogen
Greek languageIndo-European languageGreek (Modern Greek: ελληνικά, romanized: elliniká; Ancient Greek: ἑλληνική, romanized: hellēnikḗ) is an Indo-European language, constituting an independent Hellenic branch within the Indo-European language family.
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