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This is because the central atom is bigger (Pb is bigger than C) so there is less cluttering and water can easily access it. [3] Also, because of the presence of empty d orbitals on the Pb atom, oxygen can bind to it before a Pb–Cl bond has to break, thus requiring less energy. The overall reaction is thus as follow:
In the gas phase, PbCl 2 molecules have a bent structure with the Cl–Pb–Cl angle being 98° and each Pb–-Cl bond distance being 2.44 Å. [7] Such PbCl 2 is emitted from internal combustion engines that use ethylene chloride-tetraethyllead additives for antiknock purposes.
The Pb–C bond energies in TML and TEL are only 167 and 145 kJ/mol; the compounds thus decompose upon heating, with first signs of TEL composition seen at 100 °C (210 °F). Pyrolysis yields elemental lead and alkyl radicals; their interreaction causes the synthesis of HEDL. [ 14 ]
In some compounds the metal-ligand bonds may not all be at the same distance. For example in PbCl 2, the coordination number of Pb 2+ could be said to be seven or nine, depending on which chlorides are assigned as ligands. Seven chloride ligands have Pb-Cl distances of 280–309 pm.
With itself, lead can build metal–metal bonds of an order up to three. [91] With carbon, lead forms organolead compounds similar to, but generally less stable than, typical organic compounds [92] (due to the Pb–C bond being rather weak). [65] This makes the organometallic chemistry of lead far less wide-ranging than that of tin. [93]
Covalent bonds are also affected by the electronegativity of the connected atoms which determines the chemical polarity of the bond. Two atoms with equal electronegativity will make nonpolar covalent bonds such as H–H. An unequal relationship creates a polar covalent bond such as with H−Cl.
As a result, the group 14 alkyls have low chemical reactivity relative to the alkyl derivatives of other groups. In the case of carbon, the high bond dissociation energy of the C–C bond and lack of electronegativity difference between the central atom and the alkyl ligands render the saturated alkyl derivatives, the alkanes, particularly ...
The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1.