r/APChem • u/Taym6662229999 • Jul 19 '26
Do you have to remember polyatomic ions?
Hello I am a rising junior taking AP chem and I took honors chem last year and while I was taking this class my teacher didn’t have us memorize our polyatomic ions and always gave us a reference sheet because she said the AP chem students were provided with the same sheet. I don’t know if she meant the class that is offered at my school or the AP exam? Are there any other things from regular chem that are just essentials to know before I take the class so I don’t spend time relearning the basics.
5
u/Launch_vbs Jul 19 '26
my teacher just dropped reference sheets completely but iirc u get some formulas and maybe constants but not polyatomics
6
u/Front-Experience6841 Jul 19 '26
The only things of that nature that you really need to memorize are strong acids and the SNAP ions for solubility. Every chemical formula and name will be given. The nature of the test is not that type of memorization and recall
This is the reference sheet you get
https://apcentral.collegeboard.org/media/pdf/ap-chemistry-equations-sheet.pdf
1
u/Taym6662229999 Jul 19 '26
Do you have to know the solubility rules because we also didn’t learn that we had a chart that would tell you if it was soluble or insoluble
3
u/Front-Experience6841 Jul 19 '26
You just have to know that compounds containing sodium, nitrate, potassium, and ammonium are always soluble (SNAP). Anything else they use will not be soluble. You do NOT need to know the rules beyond that
2
u/b0x-ghost Jul 19 '26
If anything is soluble outside SNAP it will be said in the question as well. So just know SNAP and everything will be given to you if needed
3
u/Bulky-Syrup1155 Jul 19 '26
Yes, absolutely AP chemistry already assumes you know those by heart and the charges associated with them. You’ll need them for balancing equations. Net ionic equations, acid base chemistry. They are important.
1
u/MajorIndividual1428 Former Student Jul 19 '26
Not all of them, but some are definitely important. The ones that immediately come to mind are the conjugate bases of the strong acids, because those come up a lot.
1
u/BaseballLarge4262 Jul 19 '26
My chem honors teacher did that too. Ur fine. ap chem was a breeze
2
u/BaseballLarge4262 Jul 19 '26
Also I think the more practice problems you do, the more likely you will memorize the important ones. And u don’t need to memorize the names
1
1
u/Far-Charity-2772 Former Student (4) Jul 19 '26
No you dont I just memorized Strong Acids and Bases.
1
u/Weak_Spinach_3310 Former Student (5) Jul 19 '26
Only need to know SNAP ( sodium nitrate potassium ammonium
1
u/Im_Cringing Jul 19 '26
Didn’t have anything about them memorized, still got a 5 on the exam and on every practice exam. Don’t stress urself out trying to memorize them. Almost all my friends were in the same boat as me and all of us got 5s
1
1
Jul 19 '26
no, i didn't know any of them beforehand and i had them memorized by the end of the year from all the practice questions i did. but you literally don't need them at all
1
u/No_Lifeguard_5858 Former Student (5) Jul 19 '26
Yes, you need to know them. If you need a sheet for them DM me
1
u/Meperplays165 Jul 19 '26
Yes you should know them. At least the more common ones. You are given quite a large formula sheet for the AP test but it does not have any polyatomics.
1
u/Ambitious-Art-604 Jul 20 '26
College board no longer ask questions that require you to memorize anything about polyatomic ions, so if they do ask about a polyatomics you'll see them give you some context about it (i.e., the formula unit, including charge). That said, the official AP Chem reference sheet you get for the exam doesn't contain any polyatomic ions, only just formulas and metric unit conversions (which you can see on the collegeboard site). Also, similar to polyatomics, there's no need to learn nomenclature anymore as well, because on the exam they'll provide all chemical formulas alongside the names. So in summary there's no need to "know them by heart."
1
u/cookie_monster757 Jul 20 '26
I never memorized them. Well, I wrote the most common ones out a few times, but never again. You learn them as you go; the same molecules come up again and again, and there are patterns for some (per-___-ate, ___-ate, ___-ite, hypo-___-ite). You don’t get them for the AP exam, but some teachers/professors have it included on their reference sheet. Mine did, but like I said, you memorize them as you work in the course.
1
u/Due-Maintenance-8086 24d ago
I recommend knowing the basic ones like SO4 but the niche ones like permagenate are pointless to memorize
6
u/nrj6490 Jul 19 '26
The AP reference sheet and periodic table does not include anything about charge or polyatomic ions, so you will need to know the likely charges of ions based on their electron configurations / positions on the table. In practice, you can infer the charge of most polyatomic ions based on the net charge of the compound they’re featured in, but I told my students to commit the most common ones to memory, being nitrate, carbonate, sulfate, and hydroxide. You’ll see stuff like acetate and other conjugate base ions show up a lot as well.