What’s the oxidation state of nitrogen in $\ce{NO3-}$ ion. Simple calculation depicts that it’s $+5$. But second period elements never show variable oxidation states. And it’s structure is so confusing to me. Some people show dative/co-ordinate bonds, whereas others show a positive charge on nitrogen. Which should be considered as correct one?
What is the oxidation state of nitrogen in nitrate ion and what is its structure? [duplicate]
- $\begingroup$ Also related chemistry.stackexchange.com/q/21856/4945 $\endgroup$– Martin – マーチン ♦Jan 30, 2015 at 3:27
1 Answer
You are correct that the oxidation state is +5. The second period elements, particularly carbon, nitrogen and oxygen, do show variable oxidation states regularly.
The $\ce{NO3-}$ ion cannot be depicted using a single Lewis structure. However, its resonance structures are shown below:
What this means is that the actual structure of the nitrate ion is somewhere in between the three structures shown below. It is sometimes also depicted like this to show the symmetrical nature of the ion and the distribution of charges across it.
http://en.wikipedia.org/wiki/List_of_oxidation_states_of_the_elements http://en.wikipedia.org/wiki/Nitrate#Structure
- 1$\begingroup$ but if Nitrogen can show +5 oxidation state here, then why it cann’t form NCl5 (whereas PCl5 is possible). As per my knowledge is concerned, 2nd period elements cann’t go for octet expansion due to the abscence of vaccant d-orbital… please enlighten me.. $\endgroup$ Jan 29, 2015 at 20:59
- $\begingroup$ in nitrate the nitrogen uses its p orbitals to bond with the oxygens. however, in a hypthetical $\ce{NCl5}$ molecule the orbital overlap between the chlorine and nitrogen orbitals would be poor due to energy mismatching and steric hindrance between the chlorines and so this molecule is not stable $\endgroup$– bonJan 29, 2015 at 21:50
