Group 15 NCERT 1

Question 1

Group 15 includes nitrogen, phosphorus, arsenic, antimony and bismuth.

Answer 1

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Question 2

As we go down the group, there is a shift from non-metallic to metallic through metalloidic character. Nitrogen and phosphorus are non-metals, arsenic and antimony metalloids and bismuth is a typical metal.

Answer 2

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Question 3

Molecular nitrogen comprises 78% by volume of the atmosphere. In the earth’s crust, it occurs as sodium nitrate, NaNO3 (called Chile saltpetre) and potassium nitrate (Indian saltpetre). It is found in the form of proteins in plants and animals

Answer 3

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Question 4

Phosphorus

• Occurs in minerals of the apatite family, Ca9(PO4)6. CaX2 (X = F, Cl or OH) (e.g., fluorapatite Ca9 (PO4)6. CaF2) which are the main components of phosphate rocks.
• Phosphorus is an essential constituent of animal and plant matter.
• Present in bones as well as in living cells.
  Phosphoproteins are present in milk and eggs. Arsenic, antimony and bismuth are found mainly as sulphide minerals.

Answer 4

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Question 5

Electronic Configuration

• Valence shell configuration is ns2np3.
• S Orbitals completely filled and P orbitals half-filled, making it extra stable

Answer 5

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Question 6

Atomic and Ionic Radii

• Covalent and ionic (in a particular state) radii increase in size down the group.
• There is a considerable increase in covalent radius from N to P.
• From As to Bi only a small increase in covalent radius is observed. This is due to the presence of completely filled d and/or f orbitals in heavier members

Answer 6

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Question 7

Ionization Enthalpy

• Decreases down the group due to gradual increase in atomic size.
• Because of the extra stable half-filled p orbitals electronic configuration and smaller size, the ionisation enthalpy of the group 15 elements is much greater than that of group 14 elements in the corresponding periods.
• The order of successive ionisation enthalpies, is DeltaiH1

Answer 7

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Question 8

Electronegativity

• The electronegativity value, in general, decreases down the group with increasing atomic size.
• However, amongst the heavier elements, the difference is not that much pronounced

Answer 8

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