The key difference between ionic covalent and metallic hydrides is their formation. Ionic hydrides form when hydrogen reacts with highly electropositive s-block elements; covalent hydrides form when atoms of chemical elements having comparable electronegativity values react with hydrogen whereas metallic hydrides form when transition metals react with hydrogen.
A hydride is a chemical compound having hydrogen anion, H-. There are three major types of hydrides as ionic, covalent and metallic hydrides according to the type of chemical element that is bound to the hydrogen anion.
CONTENTS
1. Overview and Key Difference
2. What are Ionic Hydrides
3. What are Covalent Hydrides
4. What are Metallic Hydrides
5. Side by Side Comparison – Ionic vs Covalent vs Metallic Hydrides in Tabular Form
6. Summary
What are Ionic Hydrides?
Ionic hydrides are hydride chemical compounds containing a hydrogen anion bonded to a highly electropositive s-block cation. These compounds are also named as saline hydrides or pseudohalides. The combination of hydrogen and the most active metals in the alkali and alkaline earth metals groups form this type of hydride compounds. In these compounds, the hydrogen is in a negative oxidation state, having the oxidation number -1. Usually, ionic hydrides are binary compounds where only two chemical elements exist in a single molecule. Moreover, these compounds are usually insoluble in solutions.
What are Covalent Hydrides?
Covalent hydrides are hydride chemical compounds containing a hydrogen anion bonded to a comparably electronegative chemical element. In these compounds, there is a hydrogen atom and one or more nonmetal atoms that form the compound.
Figure 01: Water molecule is a Covalent Hydride Compound
There is a covalent chemical bond between the hydrogen atom and the more electropositive chemical element. This chemical bond forms when two atoms share their valence electrons. These compounds can be either volatile or nonvolatile.
What are Metallic Hydrides?
Metallic hydrides are hydride chemical compounds containing a hydrogen anion bonded to transition metal elements. These compounds are also named as interstitial hydrides. As a characteristic feature of these compounds, we can observe that these are nonstoichiometric compounds. That means, the fraction of hydrogen atoms to the metal atoms in the compound is not a fixed value. In other words, these compounds have a variable composition of atoms.
What is the Difference Between Ionic Covalent and Metallic Hydrides?
A hydride is a chemical compound having hydrogen anion, H-. We can divide hydrides into three major types according to the type of chemical element that is bound to the hydrogen anion: ionic, covalent and metallic hydrides. Therefore, the key difference between ionic covalent and metallic hydrides is the type of chemical element bound to the hydrogen anion. Ionic hydrides form when hydrogen reacts with highly electropositive s-block elements, and covalent hydrides form when atoms of chemical elements having comparable electronegativity values react with hydrogen. Meanwhile, metallic hydrides form when transition metals react with hydrogen.
Furthermore, ionic hydrides are a combination of hydrogen to a highly electropositive atom in alkali or alkaline earth group while covalent hydrides are a combination of hydrogen with a comparably electronegative nonmetal. But, metallic hydrides are a combination of hydrogen with a transition metal.
Below info-graphic summarizes the differences between ionic covalent and metallic hydrides in tabular form.
Summary – Ionic vs Covalent vs Metallic Hydrides
There are three major types of hydrides: ionic, covalent and metallic hydrides. The key difference between ionic, covalent and metallic hydrides is that ionic hydrides form when hydrogen reacts with highly electropositive s-block elements and covalent hydrides form when atoms of chemical elements having comparable electronegativity values react with hydrogen, whereas metallic hydrides form when transition metals react with hydrogen.
Reference:
1. “Hydrides.” Chemistry LibreTexts, Libretexts, 15 Aug. 2020, Available here.
Image Courtesy:
1. “Water Molecule Structure” By AbdullahAlturki99 – Own work (CC BY-SA 4.0) via Commons Wikimedia