3.25 e

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Emily 1E
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3.25 e

Postby Emily 1E » Thu May 17, 2018 4:09 pm

This question may have an obvious answer, but why does Bismuth have a 3+ charge as opposed to a 3- charge? Arsenic is in the same group as bismuth and has a 3- charge, yet bismuth can bond with 3 F- to create a neutrally charge molecule (BiFe3).

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Re: 3.25 e

Postby Chem_Mod » Thu May 17, 2018 6:50 pm

As you move down the groups in the p block of the periodic table, particularly in groups 13-15, the elements become more metallic. So Bi is more likely to bond as a cation than Arsenic is since Arsenic is closer to the top of the group and is therefore more likely to act like a non-metal and become an anion. However these rules are not always followed. Depending on what they are bound to, some elements will adapt different charges than you would expect. For example, in lecture on Friday we discussed the lewis structure of ICl4-, this means that iodine, which generally prefers to have a -1 charge would be considered to have a charge of 3+. Generally, if an element, like Bi, is bound to a more electronegative element it will have a positive charge like in the example in 3.25e. However, if Bi was the more electronegative atom in a molecule it would likely gain electrons to become negatively charged.

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