Grade 9 Chemistry, Lesson 11 - Ionic Compounds Part 2 - Free Educational videos for Students in K-12

Grade 9 Chemistry, Lesson 11 - Ionic Compounds Part 2 - By Lumos Learning

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00:00	Hey there . Welcome to Mr Lee Han teaches you
00:02	stuff . This is grade nine chemistry Lesson 11 Ionic
00:06	compounds part two compounds with multi Valent elements and Polly
00:11	Atomic ions . So we'll start off with ionic compounds
00:15	that have multi Valent elements in them . Um ,
00:18	and our question is , if iron combines with oxygen
00:20	, what does it form now ? The first thing
00:23	to note here is that iron is in this question
00:26	, and iron is not one of the 1st 20
00:27	elements . And the only reason I would put in
00:30	an element that's not one of the 1st 20 is
00:33	because it is a multi Valent element , which means
00:36	it can form multiple ions so iron can form ions
00:41	with a charge of three plus or two plus .
00:45	So we'll have to go through . Both of those
00:47	oxygen can only form a charge of two minus .
00:51	So what ? We have iron two plus and oxygen
00:54	to minus . They're both twos , so we can
00:57	ignore the charges and we end up with F O
01:02	. When we have iron three plus and oxygen to
01:05	minus . They're different . So we cross down those
01:09	ionic charges and we end up with F E 203
01:15	So when they combine , they either form F E
01:18	o or F E 203 All right . Now let's
01:22	look at how we need to name these multi Valent
01:25	Ionic compounds . When you have a multi valent ion
01:28	in an ionic compound , you have to identify what
01:31	the charges . For that multi Valent ion , you
01:36	need to include the charge in brackets . So ,
01:39	for example , F e o is iron to oxide
01:44	and its iron , too , because it contains F
01:47	E two plus F e 203 is iron three oxide
01:55	and its iron three oxide because it contains F E
01:59	three plus . So it's the chart on the ion
02:02	. That's what makes the number in the bracket .
02:06	So remember that the three and iron three oxide does
02:09	not mean the formula is f E 30 That's what
02:13	a lot of people get confused about . That's a
02:14	That's a common mistake right there . The three represents
02:19	the charge of the Iron Ion . And when you're
02:23	naming these multi valent ionic compounds , don't forget to
02:26	change the end of the non metal to ID .
02:31	All right , now we're gonna go through some examples
02:33	of ionic compounds and figure out what their name is
02:36	, so the first one . C U C l
02:39	and the second one . C u c l two
02:42	. Those are both copper and chlorine together , so
02:46	let's look at copper . Copper is a multi valent
02:49	element . It can either be two plus or one
02:52	plus , and chlorine is one minus . So we'll
02:57	just go through both possibilities and see which one's which
03:02	. So we'll start off with the two plus .
03:03	So copper two plus and chlorine . When we cross
03:07	these down , we end up with C U C
03:09	l two . So if it's copper to , it's
03:13	gonna be the second one there . So we've got
03:14	copper to chloride . The other kind of copper is
03:18	just one . And when coppers one and chlorine is
03:21	one , they're the same . So we just crossed
03:24	the moat and we end up with C U C
03:26	L . So that would be the first one .
03:30	And that must be copper one chloride . All right
03:34	, now we'll go down to the next to we're
03:36	looking at H G , which is Mercury and oh
03:40	, which is oxygen . So H G is the
03:45	multi valent element here . It can form a charge
03:48	of two plus or one plus , and then oxygen
03:52	forms a charge of two minus . So when they're
03:58	both to H G two plus and 02 minus ,
04:01	they're the same . So we just cross those out
04:04	and we end up with H G O . So
04:07	that would be the bottom one . So the bottom
04:09	one must be mercury to oxide because the charge on
04:14	the mercury is too . So the other one when
04:18	mercury is one plus oxygen is two minus . We
04:21	cross those down , we end up with H G
04:24	20 and that is Mercury one oxide . So there
04:30	you go . That's how you figure out the names
04:34	. Now we'll go the opposite way . We'll start
04:36	off with the names , and we will try to
04:38	figure out what the chemical formula is . So for
04:42	Iron three nitride , the first thing we need to
04:46	know is that nitrogen has a charge of three minus
04:50	. Now do we need to look at the periodic
04:52	table to see what charge iron has ? No ,
04:55	we don't because we've been told in the name .
04:57	That's why it's helpful . So Iron three nitride means
05:01	that iron has a charge of three plus , so
05:05	if irons three plus and nitrogen is three minus .
05:09	Then they're both threes , so they're both the same
05:11	, and we can cross them out . We just
05:13	end up with F E n . So there's the
05:16	first chemical formula . Now look at iron to nitride
05:21	. So now we know that Iran has a charge
05:23	of two plus because the numbers are different to plus
05:27	and three minus . We have to keep them and
05:29	we'll cross them down and we end up with F
05:32	E three and two . So that's iron to nitride
05:39	right now . We're into lead to fluoride . So
05:42	Florian has a charge of one minus and we know
05:46	the lead , which is P B . Has a
05:48	charge of two because it says so in the name
05:52	. So P B two plus F minus cross those
05:57	down . We end up with P B F two
06:01	. Now we'll do lead four and I tried .
06:04	So we're back to nitrogen again , which is three
06:06	minus , Um and we know the lead is four
06:11	because it says so in the name . So we'll
06:14	cross those down before it goes over to the end
06:17	. Three goes over to PB , and we end
06:20	up with PB three and four . So that's how
06:24	you figure out the chemical formulas from the name .
06:27	All right , Now we're gonna look at Poly Atomic
06:28	Ions . So , Polly atomic ions , remember ,
06:31	contain multiple elements , but they act just like one
06:35	ion . An example is phosphate , which is p
06:38	043 minus . So what is the chemical formula for
06:43	magnesium phosphate ? Well , magnesium is an alkaline earth
06:48	metal , so it has a charge of two plus
06:52	and we just said phosphate has a charge of three
06:54	minus . So just like any other iconic compound will
06:59	cross those numbers down and we end up with M
07:03	G three p 042 Now you'll notice the P 04
07:08	there is in brackets , and that's because we need
07:10	to keep that together . The reason why we need
07:14	to keep them together is because P 042 is not
07:18	the same as P 208 So a phosphate group looks
07:22	like this . So p 04 it's got three charge
07:27	of three minus . Um , so if we have
07:29	two of those , it would have a total charge
07:31	of six minus now P 208 looks very similar ,
07:38	but it actually only has a charge of four minus
07:42	um , whereas to phosphates would be six minus .
07:45	So that's not even the same chemical , and it
07:48	wouldn't behave the same , and it wouldn't use .
07:51	It wouldn't bond to as many magnesium ions . So
07:55	that's why we need to keep these things in .
07:56	Brackets keep the poly atomic ions together in a bracket
08:00	, so it's it's own separate unit . So remember
08:05	that phosphate is not the same ion as falsified .
08:10	Um , magnesium phosphate is M G three p 042
08:15	That's what we just figured out . But magnesium phosphate
08:18	guide is just magnesium and phosphorus together mg three p
08:23	two . So that's an important thing to look out
08:27	for on tests whenever you see eight at the end
08:30	. Um , it's going to be a poly atomic
08:32	ion of some sort , whereas I'd is always just
08:36	an element . So good thing to remember for a
08:39	test . So now we're gonna go through a couple
08:42	examples of finding out what the chemical formula is just
08:45	based on the name . So we'll start off with
08:47	magnesium hydroxide . Um , and first of all ,
08:51	magnesium is in the alkaline Earth Metals . Second column
08:55	of the periodic table which means it will form a
08:58	charge of two plus and hydroxide . There's no easy
09:02	way to figure this out looking at the periodic table
09:05	, but hydroxide is O H minus . So to
09:10	get the charge for a poly atomic ion like that
09:13	, you're just gonna have to remember it or have
09:16	some sort of cheat sheet . So we have mg
09:20	two plus N O . H . Minus will cross
09:23	the charges and we end up with M G O
09:26	H two . And don't forget to put the O
09:28	H in brackets Next up we have sodium hydroxide .
09:34	Now sodium is in the alkali metals is in the
09:37	first column , so it forms a charge of one
09:39	plus and we know hydroxide is one minus . So
09:44	they're both ones , which means we can cross those
09:47	out and ignore them . And we just end up
09:49	with N a . O . H . Alright ,
09:53	Next example , we're gonna look at sodium carbonate .
09:57	Yeah , so carbonate is c 03 to minus ,
10:01	and we know sodium is just one plus . So
10:06	when we cross the charges here , we end up
10:10	with yeah n a . To the 03 and our
10:19	last example here is iron three sulfate . So sulfate
10:25	is S 04 to minus . And we know that
10:28	the charge for the iron is three because it's in
10:31	the name . So f e three plus s 04
10:35	to minus . We crossed the iron charges and we
10:39	end up with F E two s 043 And don't
10:44	forget to put that Polly Atomic ion in brackets .
10:47	When you add the extra three there , All right
10:51	, now we're gonna do the reverse . We're gonna
10:53	start off with the chemical formula and try to figure
10:55	out what the name is . So for the first
10:58	one here we have mg , which is magnesium ,
11:01	and then h c 03 is something called hydrogen carbon
11:05	E . That's a poly atomic ion . So this
11:08	ends up being magnesium hydrogen carbonate . Next we have
11:14	beryllium , and then the p 04 is a phosphate
11:19	. So this is beryllium phosphate . Alright , The
11:23	next one is a little bit more tricky . We
11:26	have an eye , which is nickel and Nichols ,
11:29	not one of the 1st 20 elements . So the
11:31	only reason I would put it in a question is
11:32	because it is a multi Valent element , which means
11:37	that it's got a charge of either two plus or
11:39	three plus for its ion . So we have to
11:42	figure out which one this is now . Luckily ,
11:44	we can do a little bit of reverse engineering here
11:48	. Um , c 03 to minus is carbonate ,
11:54	so you'll see that , too . If we bring
11:57	it up from the nickel would be the tu minus
11:59	for the carbonate . And then the three would be
12:04	the three plus for the nickel when we bring it
12:06	up . So that means this must be nickel three
12:10	carbonate because that three belongs with the nickel . Now
12:15	, if we go down to the next one ,
12:17	we have nickel and p 04 which remember , is
12:20	phosphate . And if we do the same thing with
12:23	the arrows , p 04 is three minus . Yep
12:27	, that's right . That's where that three comes from
12:30	and the two then goes to the nickel . So
12:33	that must be nickel two plus , which means this
12:37	one is nickel to phosphate . So there you go
12:41	. That's the name . Well , that's it for
12:44	this video tune in Next time for Molecular Compounds ,
12:47	which will be our last Grade nine chemistry lesson .

Summarizer

DESCRIPTION:

An overview of ionic compounds with multivalent elements and polyatomic ions

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Grade 9 Chemistry, Lesson 11 - Ionic Compounds Part 2 is a free educational video by Lumos Learning.

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