A metallic element that has an incomplete inner shell. Transition elements occupy the short groups in the periodic table – i.e., groups IB through VIIB and group VIII – in which the d-orbitals are being filled. In general the transition elements are dense, hard, and of high melting point. Their electronic structures, with many loosely-bound unpaired d electrons, account for their properties: they exhibit many different valence states, form stable ligand complexes, are mostly colored and paramagnetic, and are generally good catalysts. They form many stable organometallic compounds and carbonyls (compounds in which carbon monoxide, CO, acts as a ligand) with specially stable "push-pull" bonding. The second and third row transition elements are less reactive than the first row, and stable in higher valence states. Many transition elements are technologically important.
Related categories ATOMIC AND NUCLEAR PHYSICS
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