great collection of videos, you need to win an award for being the first to do something this specific in the form of videos. No one has done it before. I promise to send something nice after my May exams this year :P thank you sir
okay did yuo mix up the melting point arrows? im confused cause you said that there are more van der waal forces so that means it should have a stronger INTERmolecular force so this means the arrow should be point down as that has a higher melting point.. and then for the group 1, melting point should point up as the positive ions are more concentrated and are more closely attracted to the delocalised sea of electrons.
I was finding it hard to understand why group 1 and 2 elements have a decreasing melting point as you go down the groups until i saw this video. Now i feel like a fool XD Thank you so much!
I had the same confusion, but then i realised that if they all lose a shell then each one going down is still bigger than the one above it. They all get smaller compared to their non-ionic form but they don't get smaller relative to each other, their relationship to each other is the same because the same thing (loss of one shell) has happened to all of them.
I am confused with the melting point one. The arrow for the alkali metals is going down while the melting point of alkali metals increases as you go up (or decreases as you go down). The same is true for halogens, the melting point increases as you go down ( or decreases as you go up) so why are the arrows pointing the other way?
it confiused me when u say up a group and sometimes down a group, it makes a big difference when it come to increaing and decresing in all trends, otherwise it helpes me a lot
Wait why would melting point increase as you go down a group? there are more electron shells and shielding so wouldnt it be easier to break bonds and therefore require less energy?
Thank you kind sir for all your videos. I had a inadequate teacher so it helped a lot. I ended up getting a 7 on chemistry SL! Thanks alot... Ah I'm missing the IB a bit aleady, never thought that would happen.
I have a question - at my school, they teach us all of these trends in terms of group and period trends...The assessment statement is quite ambiguous, but I'm pretty sure (and all of my textbooks do it this way too) that it's the trends in atomic/ionic radii, first IE, electronegativity for both periods and groups, and melting points specifically from halogens and alkali metals. Anyways, thanks so much for these videos!
you said that as you go down group 7 the melting point increases but then you drew the arrow the other way around? by the way love the vids, you are a life saver!
I would think it would be similar to the electronegativity trend for group 7, cause electrons are less attracted to larger atoms -> they're less likely to gain an electron and become an ion
how is ionic radii increasing down the group 1 when they are loosing the entire shell it's logical that the radii would decrease...or not ? pleeeease, will you explain ?
Why does Lithium have a lower electronegativity than Fluorine if they both have almost no shielding? Just out of curiosity, should add to my understanding though :) Thanks!
You probably don’t need tele answer anymore as you commented this 7 years ago but... it should be both because Fluorine has an increased nuclear charge compared to Lithium and because Fluorine is also smaller than Lithium. Having an increased nuclear charge means that Fluorine can attract electrons with more strength, like having a bigger magnet to attract the electrons, so thus its ability to attract a pair of electrons is greater than Lithium’s. Moreover, Lithium is bigger which means there’s more space between the nucleus of the atom and the electrons it’s trying to attract. Naturally, the further you’re away from a charge, the weaker it’s pull is, so the electrons are less attracted. Since fluorine is smaller than lithium, the attraction is greater. I hope this gives you a simple insight on why Lithium has a lower electronegativity. Tell me if anything I said is wrong.
Shouldn't ionic radii for metal cations get smaller as they lose electrons as the nuclear charge positive force is spread over lower shielded electrons and thus the force of attraction is larger, making them smaller?
I am a bit confused about the group trends for ionic radii. You say that it is the same trends as atomic radii, but how can the ionic radii increase for group 1 elements, when they lose their outermost shell when they form positive ions?
What does the syllabus mean with alkali metals with halogens and halogens with halide ions? Group trends should include the treatment of the reactions of alkali metals with water, alkali metals with halogens and halogens with halide ions
What does the syllabus mean with alkali metals (eg Li, Na) with halogens (F2,Cl2) and halogens (Cl2,I2)with halide ions (Br-, F-)? Group trends should include the treatment of the reactions of alkali metals with water, (as group descends reaction gets more vigorous, alkali metal hydroxide and hydrogen produced) alkali metals with halogens (salt produced) and halogens with halide ions (most reactive ends up as an ion)
You are confusing comparing a metal atoms radii to its ion - the ion is smaller it has lost a shell with going down a group each each ion has one more shell. eg Li+ = 1 shell Na+ = 2 shells K+ = 3 shells etc
Not to disrespect you or your knowledge at all (as your videos help me so much to revise, as i have a mock HL Chemistry tomorrow) But when saying 'Wan der Waals' You pronounce the 'Waals' with a V, because it's German. Great videos and thank you SO MUCH
You must totally be wrong about the ionic radii of group one elements. Even though we dont consider the loss of shell, still it loses on electron which should increase the attraction of nucles, pulling the outer shell more strongly and it should get smaller
He is wrong. Just so you know your pronunciation is perfectly fine. van der Waal is Dutch, not German and thus van is pronounced with a v and Waal is pronounced with a w, just like you've been doing in the video. :)
![S3.1.5 Trends in Metallic and Non-Metallic Properties [SL IB Chemistry]](http://i.ytimg.com/vi/gWXNjPDtZ2k/mqdefault.jpg)
![S3.1.5 Trends in Metallic and Non-Metallic Properties [SL IB Chemistry]](/img/tr.png)
![S1.3.5 Write electron configurations for atoms and ions up to Z = 36 [SL IB Chemistry]](http://i.ytimg.com/vi/vdR-qaP-gF4/mqdefault.jpg)
great collection of videos, you need to win an award for being the first to do something this specific in the form of videos. No one has done it before. I promise to send something nice after my May exams this year :P thank you sir
Mahmood Ellithy I won 3 awards - hehe. Thank you for the future gift!
okay did yuo mix up the melting point arrows? im confused cause you said that there are more van der waal forces so that means it should have a stronger INTERmolecular force so this means the arrow should be point down as that has a higher melting point.. and then for the group 1, melting point should point up as the positive ions are more concentrated and are more closely attracted to the delocalised sea of electrons.
The arrow gets thinner as it goes up group 7 , implication being that the melting point is getting lower.
I was finding it hard to understand why group 1 and 2 elements have a decreasing melting point as you go down the groups until i saw this video. Now i feel like a fool XD Thank you so much!
I had the same confusion, but then i realised that if they all lose a shell then each one going down is still bigger than the one above it. They all get smaller compared to their non-ionic form but they don't get smaller relative to each other, their relationship to each other is the same because the same thing (loss of one shell) has happened to all of them.
Great vid, thanks :D
Thanks for making it so easy to understand! I have a quiz on this tomorrow.
I am confused with the melting point one. The arrow for the alkali metals is going down while the melting point of alkali metals increases as you go up (or decreases as you go down). The same is true for halogens, the melting point increases as you go down ( or decreases as you go up) so why are the arrows pointing the other way?
Mahmood Ellithy read the comments - I agree I could have been clearer.
Big up dr flaherty
For 1st Ionization Energy, wouldn't that be the energy needed to GAIN an electron for the halogens? Because metals lose and non-metals gain?
it confiused me when u say up a group and sometimes down a group, it makes a big difference when it come to increaing and decresing in all trends, otherwise it helpes me a lot
Wait why would melting point increase as you go down a group? there are more electron shells and shielding so wouldnt it be easier to break bonds and therefore require less energy?
Thank you kind sir for all your videos. I had a inadequate teacher so it helped a lot. I ended up getting a 7 on chemistry SL! Thanks alot... Ah I'm missing the IB a bit aleady, never thought that would happen.
I have a question - at my school, they teach us all of these trends in terms of group and period trends...The assessment statement is quite ambiguous, but I'm pretty sure (and all of my textbooks do it this way too) that it's the trends in atomic/ionic radii, first IE, electronegativity for both periods and groups, and melting points specifically from halogens and alkali metals.
Anyways, thanks so much for these videos!
you said that as you go down group 7 the melting point increases but then you drew the arrow the other way around? by the way love the vids, you are a life saver!
I've made about 280/330 vids so far - I hope to finish the lot by May 2012.
Thank you for making these videos!! You're awesome!! :D
Do you think, you will have all of them done in time for the november exams?
A 7 is most excellent - off to college soon eh? Its a blast - you'll love it!
down group 7 there are more electrons so more van der waals. You need to break the intermolecular forces to melt. You are refering to the intra!
I would think it would be similar to the electronegativity trend for group 7, cause electrons are less attracted to larger atoms -> they're less likely to gain an electron and become an ion
Richard, the VDW forces are the same as London forces on the new syl, correct?
André Amaral pretty much. old syllabus = van der waal. new syllabus = London. New syllabus van der waal includes London, dipole, maybe h-bonds too!
Hey why is fluorine not included?
Why is it K--Cl instead of K--F?
the arrows are the other way round
how is ionic radii increasing down the group 1 when they are loosing the entire shell it's logical that the radii would decrease...or not ? pleeeease, will you explain ?
Why does Lithium have a lower electronegativity than Fluorine if they both have almost no shielding? Just out of curiosity, should add to my understanding though :) Thanks!
You probably don’t need tele answer anymore as you commented this 7 years ago but... it should be both because Fluorine has an increased nuclear charge compared to Lithium and because Fluorine is also smaller than Lithium. Having an increased nuclear charge means that Fluorine can attract electrons with more strength, like having a bigger magnet to attract the electrons, so thus its ability to attract a pair of electrons is greater than Lithium’s. Moreover, Lithium is bigger which means there’s more space between the nucleus of the atom and the electrons it’s trying to attract. Naturally, the further you’re away from a charge, the weaker it’s pull is, so the electrons are less attracted. Since fluorine is smaller than lithium, the attraction is greater.
I hope this gives you a simple insight on why Lithium has a lower electronegativity. Tell me if anything I said is wrong.
Shouldn't ionic radii for metal cations get smaller as they lose electrons as the nuclear charge positive force is spread over lower shielded electrons and thus the force of attraction is larger, making them smaller?
that makes sense to me - but in IB this does not apply!
OMG You're a life saver I love you man
I work at the UN - I must find a Dutch kid today to ask (What about Holland - where is the Netherlands - you are all pushing me down the rabbit hole)!
I am a bit confused about the group trends for ionic radii. You say that it is the same trends as atomic radii, but how can the ionic radii increase for group 1 elements, when they lose their outermost shell when they form positive ions?
The actual atoms (may) become smaller when they are positive ions.
BUT
the trend is still as you go down group 1 the ions get bigger i.e.
Li+
What does the syllabus mean with alkali metals with halogens and halogens with halide ions?
Group trends should include the treatment of the reactions of alkali metals with water, alkali metals with halogens and halogens with halide ions
What does the syllabus mean with alkali metals (eg Li, Na) with halogens (F2,Cl2) and halogens (Cl2,I2)with halide ions (Br-, F-)?
Group trends should include the treatment of the reactions of alkali metals with water, (as group descends reaction gets more vigorous, alkali metal hydroxide and hydrogen produced)
alkali metals with halogens (salt produced)
and halogens with halide ions (most reactive ends up as an ion)
Ah ok thanks for clearing this up!!!
Li has a lower nuclear charge so is therefore less attractive to the electrons
You are confusing comparing a metal atoms radii to its ion - the ion is smaller it has lost a shell
with
going down a group each each ion has one more shell.
eg Li+ = 1 shell
Na+ = 2 shells
K+ = 3 shells etc
Not to disrespect you or your knowledge at all (as your videos help me so much to revise, as i have a mock HL Chemistry tomorrow) But when saying 'Wan der Waals' You pronounce the 'Waals' with a V, because it's German.
Great videos and thank you SO MUCH
read the comment below - i agree it is not that clear
When the world spells sulphur and aluminium like me then I vill learn the vay to say Vaal!
PS Tell the younger chem kids about the site too!
nope, off to the army. It's mandatory here. Don't know if going to the army is a good thing or a bad thing..
you were forced to do a very bad thing
You must totally be wrong about the ionic radii of group one elements. Even though we dont consider the loss of shell, still it loses on electron which should increase the attraction of nucles, pulling the outer shell more strongly and it should get smaller
He is wrong. Just so you know your pronunciation is perfectly fine. van der Waal is Dutch, not German and thus van is pronounced with a v and Waal is pronounced with a w, just like you've been doing in the video. :)
The Dutch kid said the W is a V in Dutch.
I am confused also
Dutch rather* Apologies