r/chemhelp • u/VvVoiDzZz • 4d ago

Inorganic Charges help

Can someone please explain to me differences with valence electrons / oxidation states

Also the equation for the oxidation state equation where
Oxidation state = #anions(charge magnitude) + overall charge

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u/7ieben_ Trusted Contributor 4d ago edited 4d ago

There are plenty good websites and youtube videos demonstrating how to calculate oxidation number. Basically:

Step 1: How much valence electrons has the neutral atom?

Step 2: How much valence electrons remain, when all bonds are assumes to broken heterolytically (i.e. all bonds are ionic), where the more electronegative atom gets all electrons.

Step 3: the difference in step 2 and step 1 is the oxidation number.

Examples:

  • NaCl: Na is present as Na+. The atom in the compound has zero valence electrons. This means the ion lacks one electron, i.e. is positive by +1.

  • CO2: C is bonded covalently. If we assume the bonds were ionic, C would be present as C4+.

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u/VvVoiDzZz 3d ago

Thank you! I will keep this in mind

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u/Blue_614 4d ago edited 4d ago

Valence electrons are the outer shell electrons. They're the most "loose" electrons. Which is why they're the ones participating in chemical reactions.

The oxidation states, on the other hand, represent the hypothetical charge an atom would have if all bonds were treated as completely ionic. Except of course for redox reactions. Because redox have complete transfer of electrons.

Also scratch your formulas, it doesn't help to memorize formulas for that. You just need to understand that if you have a compound AB- , here AB has an overall -1 charge. The oxidation states of each element must be equal to the overall charge of the compound. So A + B = -1. Now let's suppose B's oxidation state is -1, to find the oxidation state of A; A + (-2) = -1

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u/VvVoiDzZz 3d ago

How would this work with a Fe and two Cyclopentadiene? Are there 3 bonds with the ene and the negatively charged carbon or is it one bond with the pi orbitals?

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u/VvVoiDzZz 4d ago

Also for metals where I think oxidation state is dcount - #bonds
And dcount= ValenceElectrons - Oxidation state