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!