Answer to a question

some anon tagged a question and i tagged the answers. but i figure i better post this, since its like a FAQ.

here goes:
anon: erm.. just wondering why OH is activating and Cl is deactivating when O is more electro-ve than Cl.

me: oh.. i mentioned it in the notes, the O atom is able to donate its lone pair to the benzene ring readily; the O atom does this(donation of LP) to a much greater extent compared to the Cl atom

but here's more

The donation( or delocalisation) of the lone pair to the benzne ring is the resonance effect
This is different from the shifting of electron density due to electronegativity differences, which is called the inductive effect.
In the case of the OH grp and the Cl grp attached to the benzene ring, you realise that the resonance effect and inductive effect are working antagonistically.
;(resonance effect means that the O and Cl atom donates electrons to the benzene ring, inductive effect means that they withdraw electron density from the ring)

its helpful if u realise that the O atom has a similar size to the C atom, so orbital overlap and electron delocalisation is an easy affair. IE, resonance effect for the O atom is very strong.

for the Cl atom, its much bigger, and so delocalisation of its LP to the C atoms in the benzene ring takes place to a much lesser extent

so in conclusion, the resonance effect for the O atom outweighs the inductive effect. The OH group is an activating group on the benzene ring.
whereas for the Cl atom, the inductive effect outweighs the resonance effect, so the Cl atom is deactivating on the benzene ring.

New Notes!

Heh anybody out there miss my notes? well here's something new...

I've made a set of notes discussing why substituents are activating or deactivating, and why the substituents are 2,4,6 or 3,5 directing

Click here!

you can also get the link from my notes homepage.

Oh yes, Please note that for deduction questions, writing line by line (as per my alkene supplementary deduction question) or in table form ( as per arenes tutorial Q5) are both alright.

But really, writing in table format is much nicer. Also something thats not been emphasized is that to do deduction questions, identifying the type of reaction is useful and important. I'll come back to that another time, maybe in another set of notes..

Meanwhile, its the holidays!! yay!!!!! actually i'm half in holiday mood. But like you all, I have lotsa work to do during the hols too. so plan your holidays well, and so that you can have fun, relax, and yet get the proper amt of work done.

have a good holiday people!

One moment in time

I was just cataloging my song collection, when i came upon this dusty old song... I've almost completely forgotten about it, but the moment i heard it, I had to listen closely again.

Its a really beautiful song, and its super super inspirational, in term of both lyrics and the melody and voice.. You can find this song moving you, whatever station in life you are at. The youngsters out there may not have heard it before.. what a pity. I will post the lyrics here, but you gotta hear the song itself.. nobody does this like whitney houston. Read the lyrics!!!

One Moment in Time - Whitney Houston

Each day I live
I want to be
A day to give
The best of me
I'm only one
But not alone
My finest day
Is yet unknown

I broke my heart
Fought every gain
To taste the sweet
I face the pain
I rise and fall
Yet through it all
This much remains

I want one moment in time
When I'm more than I thought I could be
When all of my dreams are a heartbeat away
And the answers are all up to me
Give me one moment in time
When I'm racing with destiny
Then in that one moment of time
I will feel
I will feel eternity

I've lived to be
The very best
I want it all
No time for less
I've laid the plans
Now lay the chance
Here in my hands

Give me one moment in time
When I'm more than I thought I could be
When all of my dreams are a heartbeat away
And the answers are all up to me
Give me one moment in time
When I'm racing with destiny
Then in that one moment of time
I will feel
I will feel eternity

You're a winner for a lifetime
If you seize that one moment in time
Make it shine

Give me one moment in time
When I'm more than I thought I could be
When all of my dreams are a heartbeat away
And the answers are all up to me
Give me one moment in time
When I'm racing with destiny
Then in that one moment of time
I will be
I will be
I will be free
I will be
I will be free

chilling..

heh chilling out after a long day of work again.. today ran the perfume workshop for JC2s this time round.. so closed shop at about 630pm.. its been almost a non stop 11 hr work day!

so anyways here's something chlling
happy tree friends!
funny if you like violent cartoons :P

Revision test make-up

Forthose who cannot make it to revision tests, I will conduct a make up on 21st June wednesday
9 am. venue to be cfmed.

I will do test 1 and 2 back to back.

now i think there was screw up in the database,; it got corrupted or sth so the shortlisted names are all wrong.

So if you did well in lecture test 1 and got shortlisted, you may elect to skip. but pls let me know

And if you did poorly but was not called down, my advice is, for your own sake, go.

Consultations

Dear students, I will make myself available for consultations during the june hols, for your benefit. Make sure you devise a revision plan and do your studying first. Then you can accumulate ur doubts/problems/ questions that you tried to solve but cannot do it easily.

Take the initiative to make arrangements to see me via sms, and we can work out a schedule k?

another thing about sms-ing me. Pls remember to greet me! and to identify yourself.

Also for those of you who do not understand what i'm going through in class, if so at anytime, please raise your doubts.

Another thing you will realise that the tutorials will also be more beneficial to you if u read up before coming in, since i'm more likely to focus on analysis, problem solving, and techniques, rather than go through facts covered in the notes or lectures.

I really hope that we can bring out the best thats in you.

bonding II

I'm so sorry, I was wrong abt the Mm-Sr bond. apparently its just an ion-dipole interaction...

tee hee.

but on a serious note I do love the 28 atoms...

and also to all students out there, I'm sorry if i've snapped at you recently.. i've been having a bout of insomnia and so i'm tired and impatient... that plus my bad traits = grumpy teacher.
still thats not an excuse i know.. so yes i apologise.

but in the same breath, i wish to say there are some students i'm worried about, and that's probably the reason why I'd grill them or get really ..upset with....

like for eg sometimes i ask simple recall questions with super obvious answers, and give hints, and every other student in the class has got the answer except for that one or two student.
... will resolve to find out from them whats bugging them..
for some maybe chem is not their thing, so we will need to persevere, but there are some who are not trying.. not reading notes even (so cannot answer recall questions) what should i do? punish and discipline(breeds resentment)? counsel(may fall on deaf ears)?

><

Poetry

I think i've gone mad
can you tell, what I'm writing?
Japanese haiku!

insomniac

struck with insomnia
i've lost sleep all sunday night
monday became blue

bonding

I was just observing this little container, labelled tree age.
there are 28 atoms inside and they all mostly have some happy hydrogen bonding... of course some hydrogen bonding is stronger than others..

but anyways, recently i've observed some instances of particular strong bonding formed...
like for example, element Mm and element Sr. I'm not quite sure if its just some super strong hydrogen bonding, but most likely its a stronger type of bond; the bond lengths are getting shorter and shorter.

with Mm and Sr, i wonder if its covalent or dative or ionic... do they share electrons?.. or maybe Sr has donated electrons to Mm?? Tee hee. well whether they go thru electrophilic addition to give new products, time will tell, but in the meantime, i hope their octets will be complete and happy..

I also wonder if there are more reactive species that wanna react.. I do know of at least 1 nucleophile Al that wants to donate electrons to some other unknown mysterious element. Now the question is, how do we speed up a reaction, or make it happen?

its very easy, you need to find out how to complete the other species' octet! sometimes a catalyst is also required... but most importantly, instead of just hovering around, the reactive species needs to overcome activation energy to start the reaction.

tee hee!

The worst things about me

There are three really horrible traits that i have, that i've found it so hard to change... so what's the worst things about me? here's the low-down..

1) patience.. or the lack thereof.. I have absolutely no patience.. with normal pple, i expect them to understand stuff/instructions after one repeat. at most 2 or 3. with students.. i've been conditioned after all these years to lose patience after 50 repeats. yep

2) I have a very very bad temper. Few students have really seen me lose my temper (what any of you have seen is the tip of the tip of the iceberg). When i get angry, its like a raging storm, and all hell breaks loose. I mean, when i was 18 yrs old, i was so pissed off with my (ex)girlfriend's dad so i started to scold him ( i know i know.. not a good example.. but i was young and ignorant k?).. not once, not twice, but on 3 occasions.. but yes.. once again i've been conditioned to be extra gentle with students.

bad trait (1) + bad trait (2) = errr... very bad anger management.

haha I will try to be more patient and slow to anger!