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Hydrides are anions of a hydrogen atom, which consists of two electrons. These are chemical compounds where hydrogen atoms are covalently bonded with another atom.
- Hydrides are basically compounds of hydrogen but with fewer electronegative elements.
- In these compounds, hydrogen can react with different elements of the periodic table.
- Hydrogen atoms will exhibit nucleophilic, decreasing, and fundamental properties depending on their position.
- In simple terms, if you want to understand hydrides, then it is the anion of hydrogen.
- These compounds are formed with all periodic table elements except noble gases.
- In these compounds, hydrogen exhibits an oxidation state equivalent to -1.
- Water (H2O), NH3 ( ammonia) and methane (CH4) are some common examples of hydrides.
- We can use hydrides in storage batteries.
Key Terms: Hydrides, Hydrogen, Nobel Gases, Ionic Hydrides, Covalent Hydrides, Metallic Hydrides, Oxidation State, Atoms, Periodic Table, Ions, Metal, Solutions, Anion
What are Hydrides?
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Hydrides are a type of organic compound that consists of hydrogen anion. In simple words, hydrogen anion form a covalent bond with electronegative elements.
- They usually act as Lewis bases or reducing agents.
- The molecular weight of these compounds is 1.008 g per mol.
- VA group elements do not react with hydrogen atoms, which results in the formation of a hydride gap.
- It is affected by molecular masses, intermolecular force and temperature.
- We can divide hydrides into three categories: Ionic Hydrides, Covalent Hydrides and Metallic Hydrides.
The important properties of hydrides are tabulated below:
| Category | Data |
|---|---|
| IUPAC Name | Hydride |
| Molecular Weight | 1.008 g/mol |
| Molecular Formula | H– |
| Chemical Name | Hydrogen Anion |
Hydrides
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Types of Hydrides
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Depending upon the formation of a chemical bond and the elements that can react with the hydrogen atoms, there are three types of hydrides:
Ionic Hydrides
Ionic hydrides are normally known as saline hydrides or pseudohalides. These compounds are formed between hydrogen and the most energetic metals, particularly with the alkali and alkaline-earth metals of group one and elements.
- When we analyse the structure of ionic hydrides, it has hydrogen acts as a negative charge because of the hydride ion (H−).
- They bond with greater electropositive metal atoms.
- Ionic hydrides are commonly binary compounds (i.e., the handiest two factors in the compound).
- These are non-conducting and non-volatile compounds that form crystalline structures.
- Hydrides exhibit hydrogen gas at the anode on electrolysis.
- These compounds are insoluble in solutions.
Example of Ionic HydridesExample: Sodium Hydride (NaH), Lithium hydride (LiH), Potassium hydride (KH) are Ionic hydrides. |
Ionic Hydrides
Covalent Hydrides
Covalent hydrides are formed when a hydrogen atom reacts with one or more non-metal-shaped compounds. This occurs when hydrogen is covalently bonds to greater electropositive elements with the aid of sharing electron pairs.
- These hydrides may be volatile or non-volatile in nature.
- Volatile compounds are vaporized at low temperatures.
- They exist in liquid or gas states.
- Covalent hydrides react with greater electronegativity elements of the periodic table.
- It forms a bond with elements from groups 13 to 17.
- This way, they're much less capable of donating an electron.
- As a result, they can hold them as their electron orbital is full.
- Instead of donating an H−, they would rather donate an H+ due to the fact they may be extra acidic.
Example of Covalent HydridesExample 1: One such instance of a covalent hydride is reaction between hydrogen bonds with chlorine which forms hydrochloric acid (HCl). Example 2: Boron hydride and Nitrogen hydride are examples of covalent hydrides. |
Covalent Hydrides
Metallic Hydrides
Metallic Hydrides are also known as Interstitial Hydrides. They are binary compounds of metal and hydrogen. Metal hydrides require a metallic-hydrogen bond, in which the negative charge resides at the hydrogen.
- The polarity of the metallic-hydrogen bond is M(+)…H(-).
- Most steel hydrides react violently with water to release H2 fuel and shape the corresponding metal hydroxide.
- Most metal hydrides are reactive to moisture, oxygen, and occasionally nitrogen within the air.
- As the hydrogen atom is small in size, it occupies some space in the metallic lattice, thus producing distortion.
- However, this activity does not affect its size.
- This is the reason why we call these hydrides as interstitial hydrides.
Uses of Hydrides
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The uses of hydrides are divided on the basis of type of hydrides.
Uses of Ionic Hydrides
The uses of Ionic Hydrides are as follows:
- Ionic hydrides, along with their complexes, can be used as a reducing agent.
- They are converted into dihydrogen through the heating process.
- You can use ionic hydrides as an excellent fuel material which will light up spontaneously.
Uses of Covalent Hydrides:
Covalent Hydrides can be used in organic synthesis because of their solubility in common solvents. Example: sodium borohydride.
Uses of Metallic Hydrides
Various uses of metallic hydrides are as follows:
- Metals like Ni, Pd, and Pt can absorb a large amount of hydrogen.
- They are widely used in hydrogenation as well as in catalytic reduction during the preparation of a large number of compounds.
- We can use these compounds as drying agents.
Read More:
| Class 11 Chemistry Related Concepts | ||
|---|---|---|
| Dalton’s atomic theory | Sandmeyer Reaction | Enantiomers |
| Oxidizing Agent | Alliphatic Hydrocarbons | Mitsunobu Reaction |
Things to Remember
- Hydrides are compounds which have the chemical formula H–.
- They are also known as hydrogen anions, as they consist of hydrogen forming bonds with all elements except a few noble gases.
- Ionic, Covalent, and Metallic hydrides are three hydrides, respectively.
- They are used in the technologies of storage batteries such as nickel-metal hydride batteries.
- All elements in these compounds have an oxidation equivalent to -1.
- Metal hydrides are binary compounds of metal and hydrogen.
Sample Questions
Ques. Why does the stability of hydrides decrease down the group? (2 marks)
Ans. The balance of hydrides decreases from ammonia to bismuthine. This is due to the fact that the crucial atom E increases in length down the organization. With the increase within the size of the central atom, the E-H bond turns weaker. Wherein E is nitrogen, phosphorus, arsenic, antimony, bismuth.
Ques. What are non-stoichiometric hydrides? (2 marks)
Ans. Non-stoichiometric hydrides are hydrogen deficient compounds fashioned with the aid of the response of dihydrogen with d-block and f- block elements. These hydrides do no longer comply with the regulation of constant composition.
Ques. Answer following questions: (A)What is the use of lithium hydride
(B) Mention an example of an electron-deficient hydride? (2 marks)
Ans.(A) Lithium Hydride is extensively utilized in the preparation of LiAlH4, a powerful reducing agent utilized in natural synthesis.
(B) Diborane is a perfect example of an electron-deficient hydride.
Ques. Why are ionic hydrides also referred to as salt-like hydrides? (2 marks)
Ans. Ionic hydrides, also called saline hydrides or pseudo hydrides, are known as so because of their reactivity. These salt-like hydrides are fashioned with active metals in groups 1 and 2 on the periodic table. Most of those hydrides are volatile and react with ease with an expansion of compounds.
Ques. What will happen if sodium hydride reacts with water? (2 marks)
Ans. It hydrolyses, incredibly violently, to provide sodium hydroxide and hydrogen gas (it additionally ignites on contact with air). The response is exothermic and might result in hydrogen gas igniting. As such, suitable precautions should be taken when handling it.
Ques. Explain: (A) Mention the categories into which hydrides can be classified
(B) Provide various examples for each ionic hydride as well as covalent hydride? (2 marks)
Ans. (A) Hydrides can be classified into the following three types:
- Ionic Hydrides
- Covalent or Compound Hydrides
- Metallic or non-stoichiometric Hydrides
(B) LiH, NaH are examples of ionic hydrides, whereas CH4, NH3, and H2O are examples of covalent Hydrides.
Ques. What are the uses of ionic hydrides? (2 marks)
Ans. The uses of ionic hydrides are as follows:
- Ionic hydrides, along with their complexes, can be used as a reducing agent.
- They are converted into dihydrogen through the heating process.
- This will light up spontaneously and can be an excellent fuel material.
Ques. What are Hydrides? (2 marks)
Ans. Dihydrogen under certain response conditions combines with nearly all elements, except noble gases, to form binary compounds, referred to as hydrides.
- Compounds in which the hydrogen anion is bonded to less electronegative elements are known as hydrides or hydrogen anion compounds.
- Therefore, we can say that compounds created when hydrogen combines with any element are known as hydroxides.
Ques. What is the difference between ionic and covalent hydrides? (3 marks)
Ans. The difference between ionic and covalent hydrides are as follows:
| Ionic Hydrides | Covalent Hydrides |
|---|---|
| Ionic hydrides form ionic bond. | Covalent hydrides form covalent hydrides. |
| It is a combination of hydrogen atom with electropositive atom. | It is a combination of hydrogen atom with electronegative non metal. |
| They form binary compounds. | They form stiochiometric compounds. |
Ques. What are the uses of metal hydrides? (2 marks)
Ans. The uses of metal hydrides are as follows:
- Metals with a high hydrogen absorption capacity include Ni, Pd, and Pt.
- They are extensively employed in the synthesis of several chemicals, both in hydrogenation and catalytic reduction.
- These substances function as drying agents.
Ques. Explain covalent hydrides? (3 marks)
Ans. When hydrogen interacts with other comparable electronegative elements such as Si, C, et., covalent hydrides are created. The most typical ones are NH3 and CH4. Covalent hydrides are the general term for substances created when hydrogen reacts with non-metals. The substances are either non-volatile or volatile and share a covalent bond. Covalent hydrides can also exist as gasses or liquids.
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