Random element valences

[jwnichols21]

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As I'm going thru Destroyer..

Discovered a problem where they said As (Arsenic) can have a valence of +3, -3, or +5. Is this just a special case, or is there some sort of "special bank" of elements w/ random valences they can possess that we're supposed to have memorized? Thanks.

 

[jevan]

As I'm going thru Destroyer..

Discovered a problem where they said As (Arsenic) can have a valence of +3, -3, or +5. Is this just a special case, or is there some sort of "special bank" of elements w/ random valences they can possess that we're supposed to have memorized? Thanks.

There is no "bank of elements" that don't follow the rules- but metalloids are the most likely culprits....that said, metalloids still usually follow the normal valence rules as seen with arsenic's -3 and +5 states. But if nothing works with normal valence rules, its safe to say that the metalloid has an unpredictable oxidation state.

 

[jwnichols21]

There is no "bank of elements" that don't follow the rules- but metalloids are the most likely culprits....that said, metalloids still usually follow the normal valence rules as seen with arsenic's -3 and +5 states. But if nothing works with normal valence rules, its safe to say that the metalloid has an unpredictable oxidation state.

Thanks. It came up on a Destroyer question where you had to know the missing element was +3. So if on the test to decipher what the missing valence has to be for the compound, and you're down to a Metalloid and a Transition Element, which one would you choose?

 

[jevan]

Thanks. It came up on a Destroyer question where you had to know the missing element was +3. So if on the test to decipher what the missing valence has to be for the compound, and you're down to a Metalloid and a Transition Element, which one would you choose?

umm...depends what the oxidation state of each would have to be...heres a rule- Never make the metal a negative oxidation state before putting the metalloid in a positive oxidation state.
otherwise...there is no way to know without experimental determinations-but i would change the transition metal first