NCERT Class XI Chemistry Classification of Elements and Periodicity in Properties Solutions
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Question : 17
Total: 40
How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?
Solution:
The electronic configurations of Na and Mg are :
Na :1 s 2 2 s 2 2 p 6 3 s 1
N a + 1 s 2 2 s 2 2 p 6
Mg :1 s 2 2 s 2 2 p 6 3 s 2
M g + 1 s 2 2 s 2 2 p 6 3 s 1
M g 2 + 1 s 2 2 s 2 2 p 6
The 1st ionization enthalpy of Na is lesser than that of Mg because Mg has an extra stable configuration and smaller size, so, a larger amount of energy would be required to remove an electron from the 3s orbital, which has a pair of electrons.
The 2nd ionization enthalpy of Na is more than that of Mg becauseN a + M g +
Na :
Mg :
The 1st ionization enthalpy of Na is lesser than that of Mg because Mg has an extra stable configuration and smaller size, so, a larger amount of energy would be required to remove an electron from the 3s orbital, which has a pair of electrons.
The 2nd ionization enthalpy of Na is more than that of Mg because
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