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Among the Second Period Elements the Actual Ionization Enthalpies Are in the Order Li < B < Be < C < O < N < F < Ne Explain Why Be Has Higher δIh Than B? - CBSE (Science) Class 11 - Chemistry

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Question

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why Be has higher Δithan B?

Solution 1

During the process of ionization, the electron to be removed from beryllium atom is a 2s-electron, whereas the electron to be removed from boron atom is a 2p­-electron. Now, 2s-electrons are more strongly attached to the nucleus than 2p-electrons. Therefore, more energy is required to remove a 2-electron of beryllium than that required to remove a 2p-electron of boron. Hence, beryllium has higher ΔiH than boron.

Solution 2

In case of Be (1s2 2s2) the outermost electron is present in 2s-orbital while in B (1s2 2s2 2p1) it is present in 2p-orbital. Since 2s – electrons are more strongly attracted by the nucleus than 2p-electrons, therefore, lesser amount of energy is required to knock out a 2p-electron than a 2s – electron. Consequently, At of Be is higher than that  ∆iH1 of B

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 NCERT Solution for Chemistry Textbook for Class 11 (2018 to Current)
Chapter 3: Classification of Elements and Periodicity in Properties
Q: 16 | Page no. 93

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Solution Among the Second Period Elements the Actual Ionization Enthalpies Are in the Order Li < B < Be < C < O < N < F < Ne Explain Why Be Has Higher δIh Than B? Concept: Periodic Trends in Physical Properties of Elements - Ionization Enthalpy.
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