Long Answer TypeDistinguish clearly between salt like hydrides and covalent hydrides.
| Salt like hydrides | Covalent hydrides |
| 1. Salt-like hydrides are also called ionic hydrides. | 1. Covalent hydrides are also called molecular hydrides. |
| 2. These are formed by s-block elements except Be and Mg. | 2. These are formed by p-block elements. |
| 3. These are formed by transfer of electrons from the metals to the hydrogen atoms. As such they contain H+ ions. | 3. These are formed by sharing of an electron between the element and hydrogen atoms. As such they do not contain H ions. |
| 4. They possess high melting and boiling points and conduct electricity in the fused state. On electrolysing such fused hydrides, hydrogen is liberated at the anode. | 4. They are soft, have low melting and boiling points. They have low electrical conductivity. |
| 5. They are powerful reducing agents. | 5. They are weak reducing agents. |
What do you understand by:
(i) electron deficient
(ii) electron-precise and
(iii) electron rich compounds of hydrogen?
Provide justification with suitable examples.
Short Answer TypeWhat characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reactivity ?
Long Answer TypeWhat do you understand by the term ‘non-stoichiometic hydrides’? Do you expect this type of hydrides to be formed by alkali metals?
Short Answer TypeSaline hydrides are known to react with water violently producing fire. Can CO2, a well-known fire extinguisher, be used in this case? Explain.
What do you expect the nature of hydrides if formed by elements of atomic numbers 15, 19, 23, 44 with dry dihydrogen? Compare their behaviour towards water.
Can Phosphorus with outer electronic configuration 3s23p3 form PH5?
Or
P forms PH3 but not PH5. Comment.
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