Cracking the Code of Polyatomic Ions: A Chemistry Student's Guide

In summary, the conversation discusses the importance of learning polyatomic ions in order to succeed in Chemistry. The suggestion is to memorize them, but there is a struggle with memorizing the charges. The idea of using Lewis structures to figure out charges is brought up, but it can be challenging for molecules with resonance structures. The speakers also mention that with practice, the charges for most polyatomic ions will become automatic.
  • #1
MichaelXY
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Homework Statement


I have discovered that in order to suceed in Chemistry, one must learn the polyatomic Ions. My instructor said the best way is to just memorize them, but here is the thing. Ok I can memorize that peroxide is O2, but memorizing the charges is kicking my behind. I was thinking that I should be able to figure it out using Lewis structure or something but that is not working. For example O2 means One oxygen with 6 electrons bonds with another oxygen with 6 electrons, so oxy1 gives up to electrons to fill oxy2 shell, so now oxy 1 is minus 2 electrons, so is that why O2 has a minus 2 charge? Doing a lewis structure for say Citrate loses me. Any suggestions?



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The Attempt at a Solution

 
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  • #2
if you practice your chemistry you will remember the charge for most polyatomic ions, believe me... it will come automatically after a while... just read your chemistry often...
 
  • #3
I agree; over time you'll memorize them. If you really want a systematic approach, then you could draw the Lewis structures and assign each atom a formal charge (count lone electrons as one and bonds as one). If the number matches the valence number for the atom, it is neutral.

For example, NH3 is a netural molecule because N has two lone electons + 3 bonds = 5. The valence number for nitrogen is 5, so it is neutral.

NH4+ has a positive charge because it has 4 bonds and no lone electrons = 4.

This gets harder and takes more time for resonance structures like NO2 or SO3.
 

FAQ: Cracking the Code of Polyatomic Ions: A Chemistry Student's Guide

What is the purpose of "Cracking the Code of Polyatomic Ions: A Chemistry Student's Guide"?

The purpose of this guide is to provide students with a comprehensive understanding of polyatomic ions, their properties, and how to name and write their chemical formulas. It is meant to help students master this often challenging aspect of chemistry and improve their overall understanding of chemical compounds.

What are polyatomic ions?

Polyatomic ions are charged particles composed of two or more atoms that are covalently bonded together and carry an overall electric charge. They can be either positively or negatively charged, and their charge is determined by the number and type of atoms present in the ion.

How do I name polyatomic ions?

Polyatomic ions are typically named based on their composition and charge. The name of the ion usually ends in -ate or -ite, and the prefix hypo- or per- may be added depending on the number of oxygen atoms present. It is important to memorize the common polyatomic ions and their names to effectively name them in chemical compounds.

How do I write the chemical formula for a compound containing polyatomic ions?

To write the chemical formula for a compound containing polyatomic ions, it is important to first determine the charge on each ion and then balance the overall charge of the compound. The charges of the ions must cancel out to achieve a neutral compound. It is also important to pay attention to the subscripts of each ion to ensure the correct number of each element is represented in the compound.

What are some common mistakes students make when working with polyatomic ions?

One common mistake is forgetting to account for the charges of polyatomic ions when writing chemical formulas. Another mistake is incorrectly naming the ions or forgetting to include prefixes such as hypo- or per-. It is also important to pay attention to the number of each element present in the compound and not mix up the subscripts. Practice and memorization can help avoid these mistakes.

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