Difference Between BeH2 and CaH2 Structure

The key difference between BeH2 and CaH2 structure is that BeH2 has covalent chemical bonds while CaH2 contains ionic interactions between atoms. Both these are hydride compounds having hydrogen atoms in combination with beryllium and calcium atoms, respectively. They have different structures and geometries due to the differences in electron density of each compound.

What is BeH2 Structure?
BeH2 is beryllium hydride. A single beryllium hydride molecule has a linear geometry because the beryllium atom is a group 2 atom having only two valence electrons. Both these electrons combine with the unpaired electrons of two hydrogen atoms when forming the BeH2 molecule. Since there are no other bonds or lone electron pairs in the beryllium atom, the molecule becomes linear, minimizing the steric hindrance and the repulsion between two Be-H bonds.

However, BeH2 substance is an inorganic compound, having the chemical formula (BeH2)n. And, it occurs as a colourless solid that is insoluble in solvents if the solvent cannot decompose the material. In this substance, the hydrogen atoms are bonded to the beryllium atom through covalent bonding. This is an exception from other group 2 elements because those chemical elements form hydrides which are ionic compounds. When considering the solid BeH2, it is an amorphous white solid having the hexagonal crystalline structure with a high density. This structure is reported to have a body-centred orthorhombic unit cell in a network of the corner, sharing BeH4 tetrahedra.

Although group 2 elements expect beryllium react with hydrogen, beryllium shows no reaction. Therefore, it is not easy to prepare this compound. We can prepare BeH2 via treating dimethylberyllium with lithium aluminium hydride. Also, pure BeH2 forms via the pyrolysis of di-tert-butylberyllium at a high temperature.

What is the Difference Between BeH2 and CaH2 Structure?
BeH2 and CaH2 are inorganic compounds. They are hydrides containing hydrogen atoms as the electron acceptors. BeH2 is beryllium hydride while CaH2 is calcium hydride. The key difference between BeH2 and CaH2 structure is that BeH2 has covalent chemical bonds while CaH2 contains ionic interactions between atoms. Moreover, BeH2 is a covalent compound while CaH2 is an ionic compound.