Why thermal decomposition of iron(II) nitrate and sodium nitrate yields different products?

\begin{align} \ce{4Fe(NO3)2 &-> 2Fe2O3 + 8NO2 + O2}\tag{1} \\ \ce{2NaNO3 &-> 2NaNO2 + O2}\tag{2} \end{align}

Why do nitrates of different metals decompose in different ways?

Why do we get a nitrite with sodium, but an oxide with iron(II)?

• iron (II) -> iron (III); sodium oxides are not really very stable; not comparable reaction conditions. I am quite certain, that you are not looking for reaction mechanisms in any of your recent questions. A reaction mechanism is a detailed step-by-step description in terms of elementary reactions (also including transition states). – Martin - マーチン May 26 '16 at 8:22
• @Martin-マーチン - then I'm not sure which tag to pick. I'm looking for something to help me memorize, something logically explaining the differences. I wonder why can't we have Fe(NO2)2, for instance. My latest questions are from USE Exam Sample Question No.37, considered one of the hardest in the exam. The question contains a textual description of a chain of reactions which you should write down, guessing the products. I've already memorized some interesting reactions, like SO2 + H2S (occurs in volcanoes) and am plowing further. – CowperKettle May 26 '16 at 8:49
• Maybe good tags would be [inorganic-chemistry] [redox]. – Martin - マーチン May 26 '16 at 9:18
• For the thermal decomposition of sodium nitrate see Eli S. Freeman, J. Phys. Chem. 1956, 60 (11), 1487–1493. – Martin - マーチン May 26 '16 at 11:13

• Welcome to Chemistry.SE! Take the tour to get familiar with this site. Mathematical expressions and equations can be formatted using $\LaTeX$ syntax. I disagree that $\mathrm{[Ar]\,3d^5\,4s^1}$ has a lower symmetry than $\mathrm{[Ar]\,3d^5}$. – Martin - マーチン May 26 '16 at 11:11