Variable Oxidation State Shown by Group 15 Element

Elements of group15 have 5 valence electrons in their valence shell. So they exhibit various oxidation state from – 3 to +5 as discussed below.

  1. Negative oxidation state:-  These elements has 5 electrons in the valence shells imageand require 3 more electrons to acquire nearest noble gas configuration but gain of 3 electrons is energetically not favoured. But since nitrogen is most electronegative element and smallest atom it forms image(nitride) ion by gaining 3 electrons, other elements form covalent compounds with metals and show an oxidation state of – 3 with metals
    Tendency of elements to exhibit – 3 oxidation state decreases on moving down the group from P to Bi
  2. Positive oxidation State :-  All elements show positive oxidation state from +3 and +5 on moving down the group. Stability of +5 oxidation state decrease while that of +3 increase due to inert pair effect (The inability of inner s- electrons to take part in bonding)
    Because all elements cannot lose all 5 valence electrons, they do not form
    imageions and all compounds of group 15 having +5 oxidation state i.eimageare covalent compounds.

    Nitrogen does not form +5 oxidation state compounds i.e. clip_image002[14]because it does not have vacant d- orbital’s which can enable it to extent its octet.

  3. Disproportionation :- In case of nitrogen, all oxidation states from +1 to +4 tend to disproportionate in acid solution for ex –
    image
    Similarly in case of phosphorous all intermediate oxidation states disproportionate into +5 and -3

    State in both acid and alkali solutions for ex –
    image
    However +3 oxidation states in As, Sb and Bi become increasingly stable with respect to

    disproportionation because of inert pair effect.

  4. Maximum Covalency :-  Maximum covalency of Nitrogen is 4 because it does not have vacant d- orbitals in its valence shell (n = 2). But all other element have vacant d – orbitals and can show covalency of 5 or 6 ex. image

Post Author: E-Chemistry

2 thoughts on “Variable Oxidation State Shown by Group 15 Element

  • Raj

    (June 22, 2017 - 9:35 pm)

    How is stability of oxidation states of 15th group elements varies

    • Rashmi singh

      (July 6, 2017 - 4:34 pm)

      In 15th group ,as we move down -3 and +5 oxidation state becomes less stable ,while +3 oxidation state becomes more stable, due to inert pair effect( inability of s- orbital to participate in bonding)

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