Chemistry nomenclature question

[Kendall]

We covered naming acids today.

 

 

HOCl (problem)  HClO (table in the lesson)   According to the answer key these are the same. What is the deal with the change in order? Will we encounter this again or is this a typo?

 

The text gives a table of common polyatomic ions and says that you must learn them. Then the problems use a Bromium ion that isn’t in the table.  I am assuming that because it is in the same column as Chlorine it forms the same ions with oxygen that Chlorine does and that is how the students were to figure out the name. Is this correct?

 

Do you have students memorize the ions or use the chart?

 

Is nomenclature something other kids struggle with? We have been working on the 5th chapter in Zumdahl Introductory Chemistry for 6 or 7 days now. It seems like a long time.

 

Thanks,

Kendall 

Edited September 21, 2017 by matermultorum

[MorningGlory]

Hi Kendall!

I'll jump in and try to answer the best I know how. I am a fledgling chemistry student myself---studying it hard along with six dedicated local students who are really helping me see the material from their eyes. We are using Zumdahl's World of Chemistry.

 

I have seen Zumdahl use ClO and OCl interchangeably for the hypochlorite ion in my text, too, so I googled it, and yes, it seems that both forms are acceptable. I do not know why and haven't been able to find the answer on the interwebs, so if someone knows, please tell us!

 

Bromine isn't a polyatomic ion so that is why it doesn't appear on the polyatomic ion chart. Just as you noticed...like chlorine, it is a Group 7 element so it forms a 1- anion. Yes, your student should memorize the ions that the different groups form (Group 1: 1+; Group 2: 2+; Group 3: 3+, Group 6: 2-; Group 7: 1-). 

 

And yes, your student should memorize the common polyatomic ions, their formulas, and their charges. I'm having mine work on 2-3 a day (they have already memorized 44 common elements/symbols). 

 

My class is just starting the Nomenclature chapter tomorrow. I have planned 8 full school days to cover it (but we do not plan to cover the whole textbook, so we have a little leeway with time). We hope to cover 16 of the 21 chapters in World of Chemistry. 

 

Hope that helps some! Jetta

[Kendall]

Jetta,

 

Thank you. Yes, this helps. You are very brave to do this with kids that aren't your own. I'm fumbling through with 2 of my own. I wish I had started having them memorize things sooner.  That's going in the notes for next time.

 

I am learning that I need to spend more time looking at the different ways of teaching some things, such as naming type II ionic compounds and balancing equations. There are quite a few different methods and one of my students needs certain kinds of methods to understand. Unfortunately I'm still not sure ahead of time which method will work, but I think I'm getting closer to guessing better. We'll see later this week when we start balancing equations.

 

Kendall 

[Deee]

I found the best way to learn the names compounds was to read out the proper name when I wrote equations. So instead pf saying "HCl" I would say hydrochloric acid. Eventually it stuck. I am really bad at rote learning.

[Kendall]

Great idea! 

 

[Dicentra]

Hi Kendall!

 

Jetta is right - both HClO and HOCl are hypoclorous acid.  Most of the time, you'd see the formula written as HClO but you probably see both written because organizing chemists to get them to all agree to write something the same way is about as difficult as herding cats. :D  Seriously - chemists are notoriously stubborn at giving up an older way of doing or writing something. :)

 

In terms of the question with a bromine atom, you're correct, Kendall.  There is an oxyanion series that contains oxyanions made with the various halogens (second to last column on the periodic table). :)  All the halogens form anions in combination with oxygen but the one most commonly listed is the set with chlorine that goes like this:

ClO₄^-1  perchlorate ion

ClO₃^-1  chlorate ion

ClO₂^-1  chlorite ion

ClO^-1  hypochlorite ion

 

All of the halogens will form oxyanions according to this series so bromine, for example, would form this set of oxyanions:

BrO₄^-1  perbromate ion

BrO₃^-1  bromate ion

BrO₂^-1  bromite ion

BrO^-1  hypobromite ion

 

As for memorizing the common polyatomic ions, it's not a bad idea but it all comes down to whether the teacher requires it to be memorized or not. :)  If a student is going to be continuing on with chemistry beyond a single high school course, then I would definitely get the students to memorize the ions.  It will come in very handy in future.  If this first chem course is the only one the student will ever take, the energy required to memorize is probably better spent on some other aspect of chemistry.

 

And yes - students normally have difficulty naming. :)  I have some naming flowcharts that I've created over the years (although they don't include naming of acids - I should fix that) that help students to go from names to formulae and formulae back to names.  If you're interested, just send me a PM and I'll send them to you.

 

Hope that helps!

 

[Kendall]

That all helps so much. Thanks for the thoughts on memorizing. I am beginning to think that my child that has trouble the most needs to memorize the most. I'm still experimenting. 

 

Good to know about the halogens. I was suspecting as much but the text didn't say anything about it.

 

It helps to know that students have trouble with naming. One of mine has trouble in general and so it is hard to tell what is typically hard for most kids. I will send you a PM.

[MorningGlory]

organizing chemists to get them to all agree to write something the same way is about as difficult as herding cats. :D  Seriously - chemists are notoriously stubborn at giving up an older way of doing or writing something. :)

 

Chemists aren't the only ones. Here's looking at you...botanists!!! 

 

Thank you for your thoughts on memorizing the polyatomics, Dicentra. When I attempted to tutor my niece in chemistry a few years ago, I found that she could not even recognize common polyatomic ions within a formula or name, so I purposed then to have my own students memorize at least some of them. I may have gone a bit overboard. Wouldn't be the first time. Ha!  :coolgleamA:

[Martha in GA]

I agree that it depends on the teacher. I was never required to memorize ions (although one certainly learned them as they were used so often), and I was a ChE major.

I didn't have my dd memorize ions in high school, but she is taking Chemistry for majors at the local university, and the teacher required memorization of ions.