Question

Ferric ion takes up _____ electrons to convert to ferrous ion

Answer 1

Electronic configuration of $\mathrm{Fe}$ with atomic number 26

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^6$

Electronic configuration of ferrous ion ${\mathrm{Fe}}^{+2}$is:

• A ferrous ion is formed by giving two electrons, two electrons are gone from the 4s orbital since it is the outermost orbital. but $3\mathrm{d}$ has more energy than 4s, that's why electrons are gone from $4\mathrm{s}$

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{0}3{\mathrm{d}}^6$

The electronic configuration of ferric ion ${\mathrm{Fe}}^{+3}$ is:

• A ferric ion is formed by giving 3 electrons. 2 electrons from 4s and 1 from 3d

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{0}3{\mathrm{d}}^5$

• A ferrous ion is formed by taking up 1 electron from a ferric ion

${\mathrm{Fe}}^{+3}+1{\mathrm{e}}^{-}\to {\mathrm{Fe}}^{+2}$

Conclusion: Ferric ion takes up 1 electron to convert to ferrous ion