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.

BeH2 (beryllium hydride) and CaH2 (calcium hydride) are inorganic compounds. 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.

1. Overview and Key Difference
2. What is BeH2 Structure
3. What is CaH2 Structure
4. Side by Side Comparison – BeH2 vs CaH2 Structure in Tabular Form
5. Summary

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.

Difference Between BeH2 and CaH2 Structure

Figure 01: Beryllium Hydride Structure

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 CaH2 Structure?

CaH2 is calcium hydride. It is an ionic compound and an alkaline earth hydride containing hydrogen atoms combined with calcium atoms. It appears as a grey-white powder that can rapidly react with water, giving hydrogen gas. Therefore, we can use this compound mainly as a drying agent for desiccation purposes. We can prepare CaH2 via the direct treatment of calcium with hydrogen gas at about 300 to 400 Celsius temperature.

Figure 02: Calcium Hydride Structure

CaH2 is useful as a reducing agent for the production of metals from their oxides. The metals that we can produce using this method include Ti (titanium), V (Vanadium), Nb (Niobium), Ta (Tantalum), and U (Uranium). Furthermore, this compound is useful in the production of hydrogen gas. Here, CaH2 is decomposed into Ca metal where it releases the hydrogen gas. In addition, this compound can be used as a desiccant as well.

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.

Below is a side by side comparison of the difference between BeH2 and CaH2 structure.

Summary – BeH2 vs CaH2 Structure

BeH2 is beryllium hydride while CaH2 is calcium hydride. They are hydrides containing hydrogen atoms as the electron acceptors. The key difference between BeH2 and CaH2 structure is that BeH2 has covalent chemical bonds while CaH2 contains ionic interactions between atoms.

Reference:

1. Beryllium hydride. (2020, June 20). Retrieved July 28, 2020, Available here.
2. Calcium hydride. (2020, June 25). Retrieved July 28, 2020, Available here.

Image Courtesy:

1. “Beryllium-hydride-3D-balls” By Ben Mills – Own work, Public Domain) via Commons Wikimedia
2. “Calcium Hydride (CaH2)” By Xhmikos.Original uploader was Xhmikos at el.wikipedia – Own work by Xhmikos. Transferred from el.wikipedia; transferred to Commons by User: Ferengi using CommonsHelper. (Original text: Ιδιωτικό έργο) (Public Domain) via Commons Wikimedia