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last SG · 2015-08-19T22:54:00+00:00

Topic : atomic radius Hi! This is from singapore cambridge nov a level exam year 2010,Paper 1 qn 1Qn: which element has the largest atomic radius?BrKKrScSo...

Flying grenade SG

So when halogen is added to alkene, it is the alkene nucleophile attacking the halogen electrophile to have a electrophilic addition reaction ah? (Since the more proper terms is only nucleophilic attack ah?)

Flying grenade SG

What are the factors affecting ease of Hydrolysis? Bond strength?

UltimaOnline SG

U spamming qns again. Ask 1 at a time. Wait hours for me to reply 1 qn, then post the next qn. Or I won’t reply any of them.

UltimaOnline SG

Size matters. Smaller is added to larger. X2 is smaller (in terms of no of atoms in the molecule), alkene is larger. In both elementary steps of the mechanism, it's nucleophile attack electrophile.

UltimaOnline SG

What are the factors affecting ease of Hydrolysis? Bond strength?

Depends on context. Hydrolysis of what? If C-X (Cl vs Br vs I), then yes. If acyl halides vs alkyl halides vs aryl halides, then look at sterics and electronics, which affect electrophilicity.

Flying grenade SG

Depends on context. Hydrolysis of what? If C-X (Cl vs Br vs I), then yes. If acyl halides vs alkyl halides vs aryl halides, then look at sterics and electronics, which affect electrophilicity.

Thank god

Flying grenade SG

Hi ultima, may i ask you,

https://www.dropbox.com/s/awd0smgdjlwwfsd/20160329_192327.jpg?dl=0

Can the double bond at the ring exhibit cis trans isomerism?

I cant visualise ):

Please advise if u could, thank you!

UltimaOnline SG

Hi ultima, may i ask you,

https://www.dropbox.com/s/awd0smgdjlwwfsd/20160329_192327.jpg?dl=0

Can the double bond at the ring exhibit cis trans isomerism?

I cant visualise ):

Please advise if u could, thank you!

This ring is too small to have geometric isomerism about the alkene group.

Flying grenade SG

How to know if which double bond at a ring ,

or how to deduce the size of the ring,

Such that a molecule can exhibit geometric isomerism ?

UltimaOnline SG

How to know if which double bond at a ring ,

or how to deduce the size of the ring,

Such that a molecule can exhibit geometric isomerism ?

Try googling this out for yourself, instead of me spoonfeeding you. Or better yet (Lol), ask your school teacher. See if he/she knows.

Flying grenade SG

Hi ultima, may i ask what other factors might affect this other than steric hindrance?

https://www.dropbox.com/s/2l6bxfaaarpk3wu/20160330_180801.jpg?dl=0

Qn part d)

Flying grenade SG

Ultima, may i ask u if cstoh chemistry study guide have steric hindrance? Tried finding ,flipped every page at the org chem section, cant find, index doesn't have steric hindrance also

Flying grenade SG

Depends on context. Hydrolysis of what? If C-X (Cl vs Br vs I), then yes. If acyl halides vs alkyl halides vs aryl halides, then look at sterics and electronics, which affect electrophilicity.

May i ask what do you mean by electronics?

Flying grenade SG

Nitration of methyl benzene occurs more readily than Nitration of benzene , because ch3 group donates e- into the benzene ring, hence making it more nucleophilic ah?

UltimaOnline SG

Hi ultima, may i ask what other factors might affect this other than steric hindrance?

https://www.dropbox.com/s/2l6bxfaaarpk3wu/20160330_180801.jpg?dl=0

Qn part d)

May i ask what do you mean by electronics?

CS Toh's book is the basic H2 syllabus summary, so it may lack elaborative terms such as "steric hindrance" and "electronics". It's still a must-have book for all H2 students, but students intending to score A grade should also obtain further materials in addition (not in replacement) of CS Toh's book, see my BedokFunland JC's list of recommended books for H2 Chemistry :
http://infinity.usanethosting.com/Tuition/#Books_for_H2_Chemistry

Tertiary alkyl halides (such as in ur qn part d), undergo SN1, and primary alkyl halides undergo SN2, for 2 reasons : sterics and electronics.

Sterics and electronics are also the reasons why aldehydes are more electrophilic than ketones, so if you only have 1 mole of a nucleophile reacting with 1 mole of an electrophile with both aldehyde and ketone groups present, it is the aldehyde, not the ketone, which will be the electrophilic group accepting the nucleophile.

Electronics refers to the relative magnitudes and distribution of charges (both formal charges in resonance contributors and partial charges in resonance hybrids) as a consequence of either induction or resonance or hyperconjugation (the 1st 2 of which are more important for the H2 syllabus).

https://en.wikipedia.org/wiki/Steric_effects

https://en.wikipedia.org/wiki/Electronic_effect

UltimaOnline SG

Nitration of methyl benzene occurs more readily than Nitration of benzene , because ch3 group donates e- into the benzene ring, hence making it more nucleophilic ah?

Yes of course, but you didn't specify "electron donating" by which modality, induction versus resonance.

In answering A level exam questions, you're advised to specify "electron donating by induction" or "electron donating by resonance" or "electron withdrawing by induction" or "electron withdrawing by resonance".

Flying grenade SG

Thank you

Flying grenade SG

Tertiary alkyl halides (such as in ur qn part d), undergo SN1, and primary alkyl halides undergo SN2, for 2 reasons : sterics and electronics.

https://en.wikipedia.org/wiki/Steric_effects

https://en.wikipedia.org/wiki/Electronic_effect

What about secondary alkyl halide?

UltimaOnline SG

What about secondary alkyl halide?

Teo Chee Hean : "What do you think?"

Tis the Age of the Internet,
Google by thy Sword,
Wikipedia be thy Shield

- BedokFunland JC

Flying grenade SG

Ultima are you proficient in literature ?

Bedok jc flair

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