Beryllium hydride and magnesium hydride are covalent and
polymeric. True or False

Answer

To determine whether the statement "Beryllium hydride and magnesium hydride are covalent and polymeric" is true or false, we can analyze the properties of both compounds step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Beryllium hydride is represented as BeH₂.
- Magnesium hydride is represented as MgH₂.

2. **Determine the Nature of the Bonds**:
- Beryllium (Be) and magnesium (Mg) are both alkaline earth metals. They tend to form covalent bonds due to their relatively high ionization enthalpy compared to other metals in the same group.
- Beryllium hydride (BeH₂) is known to be a covalent compound due to the small size of beryllium and its high ionization energy, which leads to a stronger covalent character.
- Magnesium hydride (MgH₂) also exhibits covalent character, although it has some ionic characteristics as well.

3. **Check for Polymeric Structure**:
- Both BeH₂ and MgH₂ can form polymeric structures. This is because they are electron-deficient species, meaning they do not have a complete octet.
- To compensate for their electron deficiency, they can form multi-center bonds, such as 3-center 2-electron bonds, where three atoms share two electrons. This leads to a polymeric arrangement.

4. **Conclusion**:
- Since both Beryllium hydride and Magnesium hydride are covalent compounds and can form polymeric structures, the statement is **True**.

### Final Answer:
The statement "Beryllium hydride and magnesium hydride are covalent and polymeric" is **True**.

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