beryllium and iodine
The elements beryllium and iodine are the only members of the boron group that contain a covalent bonding system. This allows a number of unusual organometallic compounds to be prepared. Some of the most interesting and useful organoberyllium compounds include beryllium oxide, beryllium carbonate, beryllium nitrate, and beryllium carbide.
Beryllium borides are highly soluble in water; aqueous solutions of beryllium boride have a pH range of 3.5 to 6. They can be readily precipitated as a hydrated complex with acetoanilide, a Grignard reagent, or a dialkylmercury.
Iodine is an important compound in organic chemistry and plays a role in medicine as well. Elemental iodine is toxic, and its vapour irritates the eyes and lungs. The maximum allowable concentration in air when working with iodine is 1 mg m-3.
Beryllium is a relatively stable element, with its only naturally occurring isotope, beryllium-9, having a half-life of 1.5 million years. It decays to beryllium-10 by beta decay and by two-proton emission, producing solar neutrinos.
High-resolution NMR spectra of beryllium show severe line broadening, which is caused by quadrupole moments in the nucleus. These effects are similar to those found in lithium and magnesium. However, the spectroscopic analysis of beryllium can be performed more conveniently by the use of 13C or 7Li NMR.
The element can be analyzed by photon activation bremsstrahlung with small static accelerators and, more recently, with high-energy cyclic electron accelerators such as betatron, microtron, and linac. This has allowed the synthesis of more complex, and therefore more determinable, isotopes of beryllium than ever before.