Ionic or Saline Hydrides

Hydrides are an important part of chemistry. The definition of hydrides says that any compound that has the hydrogen atom bonded with it, is known as the hydride. Hydrogen is an exceedingly reactive element. Because of this, it reacts with most metals and non-metals present in the periodic table. However, it does not react with dew noble gases. 

Many types of hydrides are present in the world of chemistry. These include ionic or saline hydrides, metallic hydrides and covalent hydrides. In this module, we will briefly discuss the importance of ionic or saline hydrides. Before we proceed towards the types of hydrides, let us have a look at the definition of hydrides. We will also analyse the importance of hydrides and their various applications.

What are hydrides?

Hydrides are any compound that contains the hydrogen atom. Usually, the hydrogen atom is bonded covalently with all the other elements present in the compound. For example, the common hydrides that we know are nitrogen hydride, potassium hydride and sodium hydride. Any compound that is a hydride is always bonded to a highly electropositive element. 

The density of the covalent bond present in the hydrides can be extreme or mild. Nevertheless, there are some exceptions to hydrides as well. For example, Boron hydride forms a multi-centred bond. Several hydrides depend on the type of molecules they have. 

Hydride can be bulk metals, oligomers, polymers or even ionic solids. Hydride also finds application in laboratories. They can be used as strong bases or reducing agents. 

Types of hydrides

Hydrides are classified into various types, depending upon their complexities with the bonds. These hydrides contain covalent bonds, metallic bonds and ionic bonds. This is the basic determining factor that divides them into three different types of hydrides. Depending on the same, they have various physical and chemical properties. This is the reason all the hydrides form different compounds when they come into contact with various other elements. There are three types of hydride:

• Ionic or saline hydrides

• Covalent hydrides

• Metallic hydrides

Ionic or Saline hydrides

Ionic hydrides are also known as saline hydrides. The other name for them is pseudohalides. Ionic or saline hydrides are formed when hydrogen forms a bond with the most active metal. These are alkali or alkaline earth metals. These metals belong to group one or two of the periodic table. 

The hydride ion bonds with the most electropositive element of the group. Ionic or saline hydrides usually have two elements in the compound. This makes them binary compounds. 

Ionic or saline hydrides react vigorously with most of the elements. Even if it reacts with water, it liberates with hydrogen gas. The ionic or saline hydrides contain the hydride ion. 

For instance, when an alkali metal is heated in the presence of hydrogen gas, an ionic hydride is produced. Further, when the alkaline metal hydride combines with water, it liberates hydrogen gas along with the hydroxide salt. 

Properties of Ionic or Saline Hydrides

Now that we have discussed the various aspects of ionic or saline hydrides let us have a look at their properties that will help us understand them better. 

• Ionic hydrides are mostly solids. They are not liquids or gases in their natural state.

• Ionic hydrides have a high boiling point. 

• They also have high density due to the presence of stable molecules.

• They have a high melting point.

• Ionic or saline hydrides are insoluble in most solvents.

• They are crystalline solids.

• Mostly, Ionic or saline hydrides are white.

• The crystalline structure of the hydrides contains ions.

• When the ionic or saline hydrides are in a liquid state, they are excellent conductors of electricity.

• They are portable and accessible sources of hydrogen.

• Many of the ionic or saline hydrides are covalent.

• Many ionic hydrides are used as reducing agents.

• Ionic hydrides are used in the synthesis of organic compounds.

• When ionic hydrides are electrolysed, they liberate hydrogen gas.

• If metal impurities are present in the hydrides, it reflects the colour grey.

Uses of Hydrides 

Hydrides find several uses in the world of chemistry. From research methods to daily needs, hydrides can be found everywhere. The various uses of hydrides are mentioned below:

• Hydrides are used as bases for the synthesis of organic compounds.

• Hydrides also find many uses in battery storage technology. 

• Hydrides are also used as reducing agents.

• They can also be used as catalysts for many catalytic cycles. The various catalytic cycles are hydrogenation, hydroformylation, and hydrosilylation. 

• Metallic hydrides find application in heat storage. 

• They are also used as drying agents.

• Ionic hydrides are excellent fuels because they liberate dihydrogen when heated. They also produce light. 

• When they combine with a bronsted acid, they liberate hydrogen gas. 

Conclusion 

In this article, we have discussed the various terms related to ionic or saline hydrides. We talked about the definition of hydrides. Hydrides are defined as a compound that contains hydrogen atoms. Usually, the hydrogen atom is bonded covalently with all the other elements present in the compound. For example, the common hydrides that we know are nitrogen hydride, potassium hydride and sodium hydride. Any compound that is a hydride is always bonded to a highly electropositive element. Hydrides are divided into three different types. They are ionic or saline hydrides, covalent hydrides, and metallic hydrides. Ionic or saline hydrides are formed when hydrogen forms a bond with the most active metal. These are alkali or alkaline earth metals. These metals belong to group one or two of the periodic table.