Beryllium and iodine form the inorganic compound beryllium iodide. It is a hygroscopic white solid. It is used in X-ray equipment and particle physics. It reacts with fluorine giving beryllium fluoride and with chlorine or bromine to give beryllium chloride or beryllium bromide. It is also used in the preparation of high-purity beryllium.
The ionic bond is formed when atoms of different elements transfer electrons to each other. This produces negative ions called anions and positive ions called cations. Because the positive and negative charges cancel out, ionic compounds are neutral in charge. Ionic substances exist as crystalline solids and have very high melting and boiling points.
Ionic bonds are generally stronger than covalent bonds. This is because the atoms involved in ionic bonding have different electronegativity values and bonding polarity. Moreover, ionic compounds usually have large differences in the sizes of their atomic orbitals. Thus they have larger kinetic energy and require more energy to break.
A strong Lewis acid, aluminum iodide reacts with water to form a purple vapor that we use as an animal stall disinfectant and as a catalyst in certain organic reactions. It can also be used to deoxygenate epoxides and cleave aryl ethers.
A common rule for naming ionic compounds is the “general rule” that similar elements or compounds with the same charge dissolve similarly. However, this rule is not always strictly followed. For example, a beryllium iodide (BeI2) compound can also be formed by mixing beryllium with iodine in the presence of oxygen to give beryllium iodide with formula BeO2. The correct chemical formula for this compound is BeI2, which has 1 atom of beryllium and 2 atoms of iodine.