0:02 the topic of this video is molecular and
0:04 ionic compounds
0:05 and the learning objectives are on your
0:08 screen so before jumping into ionic versus
0:09 versus
0:11 molecular compounds it's worthwhile to
0:14 re-emphasize what exactly an ion
0:16 is and we can do that by investigating
0:19 sodium atom on the left versus its
0:23 uh corresponding cation on the right
0:26 the only difference here um in between
0:27 the neutral atom
0:28 and the cation is the number of
0:31 electrons okay 11 electrons for the
0:33 neutral atom 10 for the
0:34 cation it lost one so that it could
0:37 achieve the noble gas configuration
0:39 um and we would predict that based off
0:42 of sodium's position in the
0:46 alkaline metals in uh group one
0:48 keeping in mind that the 11 protons and
0:51 12 neutrons are unchanged between the
0:54 neutral atom and the ion
0:57 so in the previous video i went through why
0:58 why
1:01 group 1 alkali metals and group 2 alkali
1:04 earth metals would lose 1 and 2
1:07 electrons respectively because they will
1:11 yield noble gas electron configurations
1:14 similarly elements that will become
1:17 anions that in other words they take an electron
1:18 electron
1:19 we can predict how many electrons
1:21 they'll take based off of how far away
1:22 they are from the noble gas
1:25 group in group 18. so group 17 the
1:27 halogens want to take one electron take
1:28 it to the noble gas configuration group
1:31 16. the calcagens want to take two
1:33 electrons then nicktogens in group 15
1:35 want to take three electrons
1:37 and we could even see some behavior in
1:39 group 14 such as carbon
1:43 accepting up to four electrons to um
1:45 uh to reach a double gas configuration
1:47 aluminum here in group 13 will actually
1:51 lose three electrons to go this way
1:53 back up to a neon noble gas
1:55 configuration and then also we have
1:57 transition metals that
2:00 do adopt positive charges they they will
2:01 lose electrons to form
2:04 um cations and some of the more common
2:06 charges that you'll find on transition
2:08 metals and d block metals
2:12 are shown in the middle of the screen um
2:15 so so really the the main takeaway here
2:18 is that um we tend to see
2:23 charges between metals and non-metals
2:24 we tend to see positive charges on
2:26 metals and we tend to see
2:28 negative charges on non-metals that's
2:36 figure and then also to to
2:39 expand our uh uh
2:42 ion toolkit we actually have this list
2:45 here of common polyatomic ions
2:49 now it is um incumbent upon you to
2:50 memorize the
2:52 the common polyatomic ions some of them
2:53 are a little bit
2:56 easier to memorize than others um
3:00 ammonium for example is a cation
3:02 hydronium is a cation but the rest are
3:03 going to be
3:07 anions here and
3:09 they some of them are related in a
3:11 series for example
3:13 so we can go ahead and look at the
3:15 naming convention
3:19 for perchlorate chlorate chloride and
3:25 so something to help you keep track of
3:27 these names
3:30 is the fact that
3:39 okay and hypo
3:43 in a name uh indicates under
3:47 or sort of less than eight the the the ending
3:47 ending
3:51 eight is typically reserved for
3:55 um more oxygen atoms
3:58 in the polyatomic ion whereas the
4:02 ending ite indicates fewer oxygen atoms
4:05 in the polyatomic ion and so in this
4:06 series you see
4:09 that per chlorate is sort of hyper
4:13 more oxygen atoms chlorate is just
4:16 more oxygen atoms chlorite is
4:19 fewer oxygen atoms and then hypo
4:23 under fewer oxygen atoms hypochlorite
4:25 so that can be useful but keep in mind that
4:26 that
4:30 chlorate you'll notice here has
4:34 a formula of clo3 minus
4:35 sometimes it might be tempting to think
4:37 that all eight
4:40 uh all polyatomic ions with an eight ending
4:42 ending
4:44 have three oxygens but that's not
4:46 necessarily the case
4:50 it is the case if you consider nitrate
4:56 no3 minus okay so this is nitrate
4:59 if you look to and also nitrite
5:03 has fewer oxygen atoms it's no
5:06 two minus but
5:09 this this is clearly not held up when
5:10 you look at something
5:17 because now we have an eight ending but
5:18 four oxygen
5:22 atoms so these polyatomic ions
5:24 their formulas and charges are going to
5:27 be important for you to memorize
5:29 at this point you don't need to to memorize
5:30 memorize
5:33 the uh related acid and its formula although
5:34 although
5:36 this will definitely be good to know in
5:39 the future
5:42 so now that we have um a big arsenal of
5:44 ions to consider both
5:47 um single atom ions
5:51 like sodium metal or fluoride
5:53 anion and also a big list now of
5:54 polyatomic ions
5:57 now we can actually define ionic bonds
5:59 so ionic bonds are electrostatic forces
6:01 of attraction between ions of opposite charge
6:02 charge
6:05 okay so that's just literally um
6:08 uh opposites attracting there and then
6:09 covalent bonds are when
6:12 electrons are shared between nuclei so
6:13 those are very distinct
6:16 bonding type interactions and it might
6:18 come as no surprise
6:22 that um ionic
6:25 compounds are composed of
6:29 ionic bonds ionic
6:32 compounds are
6:37 composed of ionic
6:41 bonds and
7:03 are composed of
7:07 covalent bonds
7:11 okay so with with that being said
7:13 um let's take a look here at a practice
7:17 problem and walk through
7:20 how we might predict what is an ionic
7:21 compound and what is a molecular compound
7:23 compound
7:25 so the question states uh predict
7:26 whether the following compounds are
7:29 ionic or molecular
7:32 ki h which is potassium iodide
7:35 okay uh we also have hydrogen peroxide h2o2
7:36 h2o2
7:39 we have um chloroform which is chcl3
7:43 and then we also have lithium carbonate
7:46 okay so when you want to differentiate
7:48 between an ionic and a molecular
7:49 compound you really want to be identifying
7:50 identifying
7:53 is the compound predominantly a metal
7:54 and non-metal
7:57 or predominantly non-metal
8:01 okay um so ask yourself
8:04 uh is it
8:11 non-metal if so it is likely
8:19 ionic an ionic compound
8:23 if it is a strictly
8:27 non-metal sort of main group
8:31 elements then it is likely to be
8:35 molecular okay so let's see if this
8:38 if the simple rule holds um for
8:42 option a we have
8:45 potassium and we have iodide
8:47 that's a metal and a nonmetal this would be
8:49 be
8:52 ionic compound b
8:55 hydrogen uh peroxide h2o2
8:58 hydrogen is a nonmetal oxygen is a nonmetal
8:59 nonmetal
9:02 this we would predict h
9:05 nonmetal o nonmetal this we would
9:08 predict as
9:12 molecular c
9:15 chloroform again carbon hydrogen
9:19 are and chlorine are all
9:22 nonmetals in that case so again we would
9:23 predict here
9:27 based off of c h and c l being nonmetals
9:29 that this is going to be
9:32 molecular and finally
9:36 d with lithium carbonate we have lithium
9:38 which is a metal and we actually have
9:40 carbonate here
9:42 co3 two minus which is an example of one
9:44 of our polyatomic ions
9:48 so we have a metal and we have a
9:49 non-metal or
9:51 in this particular case a polyatomic ion
9:53 and so we have two ions
9:56 this we would definitely predict is ionic
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