Search results
Results from the WOW.Com Content Network
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).
Covalent radius: the nominal radius of the atoms of an element when covalently bound to other atoms, as deduced from the separation between the atomic nuclei in molecules. In principle, the distance between two atoms that are bound to each other in a molecule (the length of that covalent bond) should equal the sum of their covalent radii.
For more recent data on covalent radii see Covalent radius. Just as atomic units are given in terms of the atomic mass unit (approximately the proton mass), the physically appropriate unit of length here is the Bohr radius, which is the radius of a hydrogen atom. The Bohr radius is consequently known as the "atomic unit of length".
155 pm – covalent radius of zirconium atom; 175 pm – covalent radius of thulium atom; 200 pm – highest resolution of a typical electron microscope [68] 225 pm – covalent radius of caesium atom; 280 pm – average size of the water molecule; 298 pm – radius of a caesium atom, calculated to be the largest atomic radius
Two contrasting examples can illustrate the variation in effects. In the case of aluminum iodide an ionic bond with much covalent character is present. In the AlI 3 bonding, the aluminum gains a +3 charge. The large charge pulls on the electron cloud of the iodine.
Carbon's covalent radii are normally taken as 77.2 pm (C−C), 66.7 pm (C=C) and 60.3 pm (C≡C), although these may vary depending on coordination number and what the carbon is bonded to. In general, covalent radius decreases with lower coordination number and higher bond order. [25]
The covalent radius of fluorine is a measure of the size of a fluorine atom; it is approximated at about 60 picometres. ... For example, BrF 5 is a molecule ...
The covalent radius of fluorine of about 71 picometers found in F 2 molecules is significantly larger than that in other compounds because of this weak bonding between the two fluorine atoms. [9] This is a result of the relatively large electron and internuclear repulsions, combined with a relatively small overlap of bonding orbitals arising ...