paucity (n.) late 14c., from Old French paucitÃ© (14c.) and directly from Latin paucitatem (nominative paucitas) fewness, scarcity, a small number, from paucus few, little, from PIE *pau-ko-, suffixed form of root *pau-(1) few, little (source also of few (adj.)).
All three molecules have four pairs of electrons around their central atom. As a result, they all have a tetrahedral arrangment of electron pairs around the central atom. The bond angle in methane, CH4, is the tetrahedral angle, i.e. 109.5 (109 28'). Ammonia, NH3, contains a lone pair of electrons, which repels the bonding electrons to give a bond angle of 107. The atoms have a trigonal pyramidal arrangement.
Simple tetrahedral complexes have four ligands arranged around the central metal ion. Again the ligands have an effect on the energy of the d electrons in the metal ion. This time, of course, the ligands are arranged differently in space relative to the shapes of the d orbitals.imple tetrahedral complexes have four ligands arranged around the central metal ion. Again the ligands have an effect on the energy of the d electrons in the metal ion. This time, of course, the ligands are arranged differently in space relative to the shapes of the d orbitals.