P Block Elements

7.44 

Nitrogen does not have d-orbital to expand its octet. So, it cannot have coordination number greater than 4. But, phosphorous has d-orbital and can extend its octet and form R₃P = O. Therefore, R₃P = O exist but R₃N = O does not.

7.43

Among the group 15 elements, N has the highest electronegativity, because of which there is high electron density around N. This causes repulsion between the electron pairs around causing high HNH angle value.

As we go down the group, the electronegativity of the elements decease and the bond ang

7.42 

To draw the resonating structure of NO₂ No. of valence electrons for N = 5

No. of valence electrons for O = 2 × 6 = 12

Total no. of valence electrons = 5 + 12 = 17

The N and O atoms are arranged in such a way that the less electronegative atom N is placed as the central atom.

Electron pairs ar

7.41

Copper metal on reaction with HNO₃ gets oxidized and give different by-products depending on the temperature, concentration of the acid and the copper metal undergoing oxidation.

The reaction of copper with concentrated and dilute HNO₃ is as shown below:

3Cu + 8HNO₃ (did.)  3Cu (NO₃)₂ + 2NO +

7.40

Ammonia is manufactured industrially by Haber's process. Nitrogen from gas is combined with hydrogen derived from natural gas (methane) in the ratio 1:3 giving rise to ammonia. The reaction is reversible and exothermic.

The optimum conditions for the manufacturing of ammonia are pressure 200*10⁵

7.39

Nitrogen is prepared in the laboratory by heating aqueous ammonium chloride (NH₄Cl) with sodium nitrite (NaNO₂) to form ammonium nitrite (NH₄NO₂), which is unstable. Ammonium nitrite breaks down to form nitrogen and water.

NH₄Cl (aq) + NaNO₂ (aq)  - NH₄NO₂ + NaCl (aq)

NH₄NO₂  - N₂ (g)+ H

7.38 

The electronegativity of N (3.0) is higher than that of P (2.1). Due to this N-H bond is more polar than a

P-H bond. Also, P and H have the same electronegativity of 2.1 i.e., the P-H bond is non-polar. Therefore, PH₃ does not form hydrogen form.

The structure of NH₃ and PH₃ with their elect

7.37 

Chemical reactivity of group 15 elements towards hydrogen, oxygen, halogens, and metals are discussed below.

Reactivity towards hydrogen: Group 15 elements react with H to form hydrides of type EH3 where E=N, P, As, Sb or On moving down from NH₃ to BiH₃, the stability of the hydrides decrea

7.2

Nitrogen atom can bond with another nitrogen atom by strong p–p overlap resulting in NN. The triple bond in N₂ has high bond strength resulting in high bond dissociation energy. Phosphorous do not show this property of p–p overlap. Hence, nitrogen is less reactive than phosphorous.

The p-orbitals

7.1

The general characteristics of Group 15 elements are:

Electronic configuration: All Group 15 elements have 5 electrons in their valence The general electronic configuration of these elements is ns² np³

Oxidation state: Group 15 elements have 5 valence electrons and they require 3 more electrons to