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.
The d x 2 -y 2 and d z 2 orbitals on the metal ion at the center of the cube lie between the ligands, and the d xy, d xz, and d yz orbitals point toward the ligands. As a result, the splitting observed in a tetrahedral crystal field is the opposite of the splitting in an octahedral complex.Because a tetrahedral complex has fewer ligands, the magnitude of the splitting is smaller.o understand the splitting of d orbitals in a tetrahedral crystal field, imagine four ligands lying at alternating corners of a cube to form a tetrahedral geometry, as shown in the figure below.