NEET Chemistry Classification of Elements and Periodicity in Properties / तत्त्वों का वर्गीकरण एवं गुणों में आवर्ति NEET PYQ-Classification Elements In Properties

  • question_answer
    Correct order of Ist ionisation potential (I.P.) among following elements Be, B, C, N, O is:        [AIPMT 2001]

    A)        \[B<Be<C<O<N\]      

    B)  \[B<Be<C<N<O\]

    C)  \[Be<B<C<N<O\]

    D)       \[Be<B<C<O<N\]

    Correct Answer: A

    Solution :

    Ionisation potential: The amount of energy required to remove an electron from the outer-most orbit of a gaseous atom is known as ionisation potential. Elements having half-filled or completely filled orbitals are more stable than partially filled orbitals.
    In a period from left to right ionisation potential decreases as the atomic number increases. The given elements (Be, B, C, N, O) are present in II period as
    \[\xrightarrow[\text{Ionisation potential increases}]{Be\,\,\,\,\,\,\,\,\,B\,\,\,\,\,\,\,\,C\,\,\,\,\,\,\,N\,\,\,\,\,\,\,O}\]
    But in case of Be and B, ‘Be’ has higher ionisation potential due to stable configuration.
    \[_{4}Be=1{{s}^{2}},\,2{{s}^{2}}\]
    \[\] Stable configuration
    \[_{5}B=1{{s}^{2}},2{{s}^{2}},2{{p}^{1}}\]
    \[\] Unstable configuration
    In the same way in case of ‘N’ and ‘O’, ‘N’ has higher LP. than ‘O’ due to stable configuration
    \[_{7}N=1{{s}^{2}},2{{s}^{2}}2{{p}^{3}}\]
    \[\,\,\text{Stable}\,\text{configuration}\]
    \[_{8}O=1{{s}^{2}},2{{s}^{2}}2{{p}^{4}}\]
    \[\,\,\text{Unstable}\,\,\text{configuration}\]
    So, the correct order of increasing IP will be:
    \[B<Be<C<O<N\]


You need to login to perform this action.
You will be redirected in 3 sec spinner