Question
Question: Which of the following is the correct order of ionisationenthalpy ?...
Which of the following is the correct order of ionisationenthalpy ?
A
Be+> Be
B
Be > Be+
C
C > Be
D
B > Be
Answer
C > Be
Explanation
Solution
(1) Be has completely filled stable valence shell configuration i.e. 2s2 while in Be+ because of positive charge, the removal of electron requires much higher energy. So, ionisation energy of Be+ is greater than Be.
(3) Across the period, atomic size decreases and nuclear charge increases and thus valence shell electron(s) is/are tightly held by nucleus. So, ionisation energy of C is greater than Be.