Hydrides and its classification #MCQ

Savitribai Phule Pune University #SPPU
MSc I
CHP 130 Sec I
#Chemistry #Msc
#MCQ

1. Hydrides And I ts C lassification Tushar Dahake Abasaheb Garware College Pune

2. HYDRIDES Hydride, in simple terms, is said to be the anion of hydrogen, H − Hydrogen molecule usually reacts with many elements except noble gases to form binary compounds called hydrides. water is a hydride of oxygen, ammonia is a hydride of nitrogen, etc

3. Types of hydrides (ii) Ionic or saline or salt-like hydrides ( i) Covalent or molecular hydrides (iii) Metallic hydrides Hydrides are classified into three major groups, depending on what elements the hydrogen bonds to and based on their physical and chemical properties.

4. Covalent or molecular hydrides They consist of discrete covalent molecules with are held together by weak Vander Waal's forces of attraction. They are usually formed with p-block elements. They are volatile in nature. They have low melting and boiling point.  They do not conduct electricity. Familiar examples are Methane (CH4), ammonia (NH3), water (H2O) and hydrogen fluoride (HF). These covalent hydrides are gases in nature with exception of water

5. Molecular hydrides are further classified on the basis of a number of electrons and bonds in the Lewis structures as, 1.Electron rich hydride 2.Electron precise hydride 3.Electron deficient hydride

6. In which there is more electron pair on the central atom that is needed for bond formation. (i.e. there are lone pair on the central atom). Nitrogen, oxygen and fluorine family In which all electron of the central atom is engaged in bond. It has the presence of two centers and two electron bond and the absence of lone pair of the central atom. In this compound less number of electron is present than expected. Boron Family Carbon Family

7. Ionic or saline or salt-like hydrides These are stoichiometic compounds of hydrogen formed with most of the s−block elements. i.e., alkali and alkaline earth metals. These hydride are crystalline, non volatile and non-conducting solid state.  They have high melting and boiling points. Alkali metal hydrides are LiH, NaH, KH, RbH, CsH and alkaline earth hydrides MgH2, SrH2, BaH2, CaH2.

8. Metallic hydrides The elements of the group 3, 4, 5, (‘d’ block) and ‘f’ block elements react with hydrogen and form metallic hydrides Metallic hydrides are non-stoichiometric because hydride forms in ‘d’ block are interstitial hydrides means these hydride occupies vacant sites of empty space in the crystal lattice of metals electrically conducting solid with a metallic luster. They are hard. The elements in the middle of the d-block do not form hydrides. The absence of hydrides in group 7, 8 and 9 of the periodic table is sometimes called the hydrogen gap , These metals have low affinity for hydrogen in  their normal oxidation state. Metallic hydrides are usually prepared by heating the metal with hydrogen under high pressure Example of Metallic Hydrides :  TiH aluminium, cadmium, magnesium, etc.

9. MCQ Which of the following hydrides are generally nonstochiometric in nature? (a) Ionic Hydrides (b) Molecular Hydrides (c) Interstitial Hydrides (d) All of the Above . Answer: (c) Interstitial Hydrides Which of the following is a saline hydride? HCl (b ) SiH4 (c) NaH (d) NH3. Answer: (c) NaH Which of the following hydrides is electron-precise hydride? (a) B2H6 (b) NH3 (c) H2O (d) CH4 Answer: (d) CH4

10. Only one element of ________ forms hydride . (a) group 6 (b) group 7 (c) group 8 (d) group 9 Answer: (a) group 6 Which of the following statements is correct? (a) Elements of group 15 form electron deficient hydrides. (b) All elements of group 14 form electron precise hydrides. (c) Electron precise hydrides have tetrahedral geometries. (d) Electron rich hydrides can act as Lewis acids . Answer: (b) & (c) Which of the following statements is correct? (a)Hydrides of group 13 act as Lewis acids. (b) Hydrides of group 14 are electron deficient hydrides. (c) Hydrides of group 14 act as Lewis acids. (d) Hydrides of group 15 act as Lewis bases. Answer: (a) & (d)

11. Thank You!