Two skills that extend off this basic idea that are the focus of this blog post.
1. Write chemical formulas and names for the ionic compounds containing metals with multiple oxidation states (typically transition metals).
2. Write chemical formulas and names for ionic compounds containing polyatomic ions.
Here is a video that provides a quick 5-minute treatment of writing formulas of ions with multiple oxidation states:
The naming of ionic compounds with multiple oxidation states using Roman numerals was defined for general use in 1970 -- here is the publication produced by the International Union of Pure and Applied Chemists:
Before this, the naming system was a little more challenging to negotiate with suffixes such as "ic" and "ous" . Here is a page to provide some historical perspective:
Another challenge in ionic formula writing is a compound with more than two elements, usually involving a polyatomic ion. Here is an 11-minute video segment addressing this formula writing challenge:
He does discuss whether chemists write the parentheses in formulas, and I agree completely with those guidelines.
For my beginning students, I did allow the use of parentheses around the polyatomics, even if the subscript was the unwritten "1" -- this was just to learn to work with the polyatomics comfortably. I considered the parentheses as sort of a "magic shield" so that anything inside the parentheses stayed the same and the criss-cross occurred outside the parentheses.
This was simply a learning tool I used to make the formula writing with polyatomics less intimidating.
It is the teacher's choice of whether to have students memorize polyatomic ions. A list is in the NYS Regents Reference Table E:
In an Honors Chemistry course I taught, quizzes of (1) the polyatomic ions and (2) of ionic formula writing /naming was given.
For both quizzes, the student was given three tries for a highest score because the only reference was a periodic table without any charges, and there was no reference table of polyatomic ions.
This particular quiz policy was a precedent before I started teaching the course. One quiz was given in class, the other two were given after school -- the highest score of the three was the quiz that counted. I did observe significant improvement and it encouraged student mastery of these concepts.
Here are some worksheets focusing on ionic formula naming and writing:
This site contains several pages about ionic formula naming/ writing from which to choose:
This ionic formula worksheet has answers:
Here is more practice with binary ionic compounds:
And here is more practice with polyatomic ions:
If you are looking for another Chemistry subject, check out my Topic List -- it could help you to find past Blog entries.
*Another reference I just found is a TED Periodic Table that links the viewer to video clips about each particular element:
Check it out!
Buy my lab book "Chemistry on a Budget" -- it is available for $20 at amazon.com or $23 at lulu.com:
This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the choice of format! Each lab is two pages to allow for one two-sided handout.
I've edited this post to smooth out a few edges. I appreciate your patience during this gap in blog posts.
I will post briefly about Molecular Formula Writing this Friday, October 31st.
Have a good week!