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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Achrelos on September 18, 2013, 08:34:11 PM

Title: How do polyatomic ions form?
Post by: Achrelos on September 18, 2013, 08:34:11 PM
I am confused about this and my professor said she didnt want to get into it. I looked up some Lewis dot structures to see if I could figure it out and I think I did but I wanted to be sure. For simplicity's sake I will use Ammonium. So the formula is NH4+. Nitrogen can only make three bonds, so the fourth H shouldnt be there. The way I understood what I saw was that it is actually an H+ ion, and it attracts to the 2 loose electrons on th N. Is that correct?

Do they form as a result of one of the atoms being ionic? If not, how do they form?

Sorry if I rambled.
Title: Re: How do polyatomic ions form?
Post by: Borek on September 19, 2013, 03:02:24 AM
Yes, proton sticks into a free electron pair on the nitrogen.

Please note that Lewis structures are only an approximation - they don't have to work, especially for compounds containing elements from 3rd period up. At early stages of learning chemistry it is better to accept some things happen (like "polyatomic ions form") and don't get int hows/whys, as you don't know yet enough for a good explanation, and bad explanation (one that is way oversimplified) makes more harm than good.