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The Bohr radius is consequently known as the "atomic unit of length". It is often denoted by a 0 and is approximately 53 pm. Hence, the values of atomic radii given here in picometers can be converted to atomic units by dividing by 53, to the level of accuracy of the data given in this table. Atomic radii up to zinc (30)
The atomic radius of a chemical element is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the outermost isolated electron. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius.
The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the International System of Units (SI), equal to 1 × 10 −12 m, or one trillionth ( 1 / 1 000 000 000 000 ) of a metre, which is the SI base unit of length.
298 pm – radius of a caesium atom, calculated to be the largest atomic radius; 340 pm – thickness of single layer graphene; 356.68 pm – width of diamond unit cell; 403 pm – width of lithium fluoride unit cell; 500 pm – Width of protein α helix; 543 pm – silicon lattice spacing; 560 pm – width of sodium chloride unit cell
Polonium 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 neighbors in the periodic ...
The covalent radius, r cov, is a measure of the size of an atom that forms part of one covalent bond. It is usually measured either in picometres (pm) or angstroms (Å), with 1 Å = 100 pm. In principle, the sum of the two covalent radii should equal the covalent bond length between two atoms, R (AB) = r (A) + r (B).
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice .
The kinetic diameter is not the same as atomic diameter defined in terms of the size of the atom's electron shell, which is generally a lot smaller, depending on the exact definition used. Rather, it is the size of the sphere of influence that can lead to a scattering event.