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.
Basically, electron pairs in a molecule want to adopt a geometry to maximize their distance apart, since like charges repel each other. For example, methane (CH4) adopts a tetrahedral arrangement - you can think of this as the carbon atom at the center of a pyramid and the 4 hydrogens at the four vertices. Bonds angles are 109.5 degrees. This is a case where all electrons are bonding electrons; they form the 4 bonds between carbon and hydrogen. Lone electron pairs also affect the geometry. For instance, water (H2O) has two lone electrons pairs; it adopts a bent/angular geometry.