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