BeH2 Structure vs. CaH2 Structure

What's the Difference?

The BeH2 structure and CaH2 structure are both examples of hydride compounds, but they differ in terms of their bonding and overall structure. BeH2 has a linear molecular structure, with beryllium (Be) at the center and two hydrogen (H) atoms attached to it. This linear arrangement is due to the sp hybridization of beryllium, which allows for the formation of two sigma bonds with the hydrogen atoms. On the other hand, CaH2 has a crystal lattice structure, where calcium (Ca) ions are surrounded by hydride (H-) ions. The calcium ions are arranged in a face-centered cubic lattice, with each calcium ion surrounded by eight hydride ions. This ionic bonding results in a solid, high-melting-point compound. Overall, the BeH2 structure is molecular and linear, while the CaH2 structure is ionic and crystalline.


AttributeBeH2 StructureCaH2 Structure
Chemical FormulaBeH2CaH2
Number of Atoms33
Bond TypePolar CovalentIonic
Electronegativity Difference1.71.2
Molecular Weight11.03 g/mol42.10 g/mol
Boiling PointNot AvailableNot Available
Melting PointNot AvailableNot Available

Further Detail


When it comes to studying chemical structures, understanding the attributes of different compounds is crucial. In this article, we will compare the attributes of two important compounds: BeH2 (beryllium hydride) and CaH2 (calcium hydride). Both compounds are hydrides, meaning they contain hydrogen as a central element. However, they differ in terms of their atomic composition, bonding, physical properties, and reactivity. Let's delve deeper into these attributes to gain a comprehensive understanding of BeH2 and CaH2 structures.

Atomic Composition

BeH2 consists of beryllium (Be) and two hydrogen (H) atoms. Beryllium is a light alkaline earth metal with an atomic number of 4 and a valence of +2. It has a small atomic radius and forms stable covalent bonds. On the other hand, CaH2 contains calcium (Ca) and two hydrogen (H) atoms. Calcium is also an alkaline earth metal but has a larger atomic radius compared to beryllium. It has an atomic number of 20 and a valence of +2. The atomic composition of these compounds plays a significant role in determining their properties.


BeH2 and CaH2 exhibit different types of bonding due to the nature of their constituent elements. Beryllium in BeH2 forms covalent bonds with the hydrogen atoms. Covalent bonding involves the sharing of electron pairs between atoms, resulting in the formation of a stable molecule. In BeH2, beryllium shares its two valence electrons with two hydrogen atoms, forming two covalent bonds. On the other hand, CaH2 exhibits ionic bonding. Calcium, being an alkaline earth metal, readily loses its two valence electrons to form a stable cation (Ca2+). The hydrogen atoms then accept these electrons, forming stable hydride ions (H-). The electrostatic attraction between the oppositely charged ions leads to the formation of an ionic compound.

Physical Properties

The atomic composition and bonding in BeH2 and CaH2 influence their physical properties. BeH2 is a colorless gas at room temperature and pressure. It has a molecular weight of approximately 11.03 g/mol and a boiling point of -53.5°C. Due to its low molecular weight, BeH2 is a light compound. On the other hand, CaH2 is a white crystalline solid. It has a higher molecular weight of approximately 42.10 g/mol and a melting point of 816°C. The solid state of CaH2 indicates stronger intermolecular forces compared to the gaseous state of BeH2. These physical properties are a result of the different atomic compositions and bonding in the two compounds.


BeH2 and CaH2 also differ in terms of their reactivity. BeH2 is a highly reactive compound due to the presence of beryllium, which readily forms covalent bonds. It reacts violently with water, releasing hydrogen gas and forming beryllium hydroxide. The reaction is exothermic and can be hazardous. On the other hand, CaH2 is less reactive compared to BeH2. It reacts with water to produce hydrogen gas and calcium hydroxide. However, the reaction is not as vigorous as that of BeH2. CaH2 is often used as a drying agent due to its ability to react with water and remove moisture from a system.


Both BeH2 and CaH2 find applications in various fields. BeH2 is used in the production of beryllium metal, which has excellent thermal conductivity and is used in nuclear reactors, aerospace components, and X-ray windows. It is also utilized in the synthesis of organic compounds and as a catalyst in certain chemical reactions. CaH2 is primarily used as a drying agent in laboratories and industries. Its ability to react with water makes it useful for removing moisture from solvents and gases. Additionally, CaH2 is employed in the production of hydrogen gas, which has applications in fuel cells and as a reducing agent in various chemical processes.


In conclusion, BeH2 and CaH2 structures exhibit distinct attributes in terms of atomic composition, bonding, physical properties, reactivity, and applications. BeH2 consists of beryllium and hydrogen, forming covalent bonds, while CaH2 contains calcium and hydrogen, forming ionic bonds. BeH2 is a gas, while CaH2 is a solid. BeH2 is highly reactive, whereas CaH2 is less reactive. Both compounds find applications in various industries. Understanding these attributes is essential for scientists and researchers working with these compounds, as it helps in predicting their behavior and exploring their potential applications.

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