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Naming Compounds with Polyatomic Ions



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We'll cover plenty of examples going from the compound name to the chemical

formula and from the chemical formula to the compound name because naming

compounds doesn't have to be complicated. Hello everyone I'm Melissa Maribel

your personal tutor and before we get to the examples here are three things you

really need to know for naming compounds with polyatomic ions. Important thing one:

to name an ionic compound with a polyatomic ion the name will consist of

the name of the metal followed by the name of the polyatomic ion and

everything is in lowercase. Important thing two: when finding the chemical

formula from the compound name we will always have to balance out the charges

for ionic compounds and these are the charges you will need to have memorized.

So if you have to pause the video and write these down please do so. Important

thing three: now polyatomic ions, polyatomic meaning it's composed of two

or more atoms an ion meaning it has an overall charge. Here's a list of common

polyatomic ions you will need to know and your teacher should also provide you

with a list. Now you're ready for the three examples plus at the end I'll

teach you a trick on how to memorize the polyatomic ions even faster. Example 1:

same charges we are given the compound name of magnesium carbonate and asked to

find the chemical formula so let's first identify the symbol for magnesium and

its charge. Magnesium has a charge of 2 plus next we'll identify what carbonate

is and its charge using our common polyatomic ion table we'll see that

carbonate is CO3 with a 2 minus charge. Since we have the same charges

there is no need for an additional subscript since our charges are already

balanced so this is our chemical formula. Going from the chemical formula to the

compound name we will identify the name of the metal and the name of the

polyatomic ion. This is lithium and this is acetate the

compound name is then lithium acetate. Example two: different charges our given

compound name is aluminum sulfate and we are finding the chemical formula so

identify the symbol and the charge of aluminum which is Al with a 3 +

charge and sulfate is SO4 with a 2- charge. Since this is an ionic compound

we must balance the charges to balance the charges the charge of sulfate now

becomes aluminum's new subscript and the

charge of aluminum now becomes the new subscript for sulfate. Note: whenever a

polyatomic ion requires a subscript we will place the entire polyatomic ion in

parenthesis with the added subscript outside of the parenthesis so this is

our chemical formula. Now going from the chemical formula to the compound name we

will identify the name of the metal and the name of the polyatomic ion. Ca is

calcium and OH is hydroxide. So our compound name is calcium hydroxide.

Example 3: both are polyatomic ions given the compound name of ammonium sulfate

we'll find the chemical formula by identifying each type of polyatomic ion

and their charges ammonium is NH4 with a 1 + charge and sulfate is SO4 with

a 2- charge. To make the charges the same the ammonium needs a 2 subscript so

ammonium will be in parenthesis with a 2 subscript outside of the parenthesis

followed by SO4 and this is our chemical formula. Now going from the

chemical formula to the compound name we will identify each polyatomic ions name

NH4 is ammonium and NO3 is nitrate the compound name is then

ammonium nitrate. Ok here's the trick on how to remember all the polyatomic ions

faster. Most polyatomic ions end in either ite

or ate. Notice how the ones ending in ate have one

more oxygen than the ones ending in ite. There's the trick the ates have one

more oxygen than the ite. Now you only have to remember the ates so this cuts

your memorizing in half. This topic is so important that's why I created several

videos and I designed a how-to guide on naming compounds and acids that includes

over 30 pages of detailed examples and explanations all to save you time and

get it right the first time around the link to shop my notes is in the

description box along with other helpful resources like homework help and

tutoring and so much more and remember stay determined you can do this!