âSorry for the paucity of posts over the past few days but I'm in a state of upheaval known as âjob changeâ.â âThere is no scheme in all these projects to solve the paucity of clean, safe drinking water.â âThe paucity of these qualities in the present Republic would stagger them.â
Benzene is the archetypical aromatic compound. It is planar, bond angles=120Âº, all carbon atoms in the ring are sp2 hybridized, and the pi-orbitals are occupied by 6 electrons. The aromatic heterocycle pyridine is similar to benzene, and is often used as a weak base for scavenging protons.
We start with the symmetric possibilities, H2O, OF2, and OCl2. The bond angles and bond lengths of these three molecules are shown below: Note that the bond lengths increase in a way we can understand easily: H is smaller than F, which is smaller than Cl. But look at the bond angles. We have claimed that the two lone pairs on the O atom (not shown) should push the bonding pairs of electrons down, lowering the bond angle from the perfect tetrahedral angle of 109.47Â°.