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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 346366 times)

holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #270 on: March 03, 2010, 03:23:47 pm »
Thats more like metallic bonding....

IS BORON a semi metal ??







WHERE is NID ???
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Offline SGVaibhav

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #271 on: March 03, 2010, 03:47:33 pm »
Quote from: Ari Ben Canaan on March 03, 2010, 03:23:47 pm
Thats more like metallic bonding....

IS BORON a semi metal ??







WHERE is NID ???
add small holes between metallic bonding to make it look like a alloy..
(like u see small black circles in my diag)


no boron is a non-metal..
i dont know where is nid..

answeered all ur questions :D :D :D
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Offline Saladin

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #272 on: March 03, 2010, 04:00:30 pm »
actually it will have more of a diamond like structure.
http://upload.wikimedia.org/wikipedia/commons/8/8f/Silicon-carbide-3D-balls.png

Because Carbon and Silicon have the same bonding abilities.

Combining carbon and silicon will fore somewhat of a semi conductor. U dont need to show free electrons because there arent any.

Secondly, in semi conductors, the electrostatic force between te nucleus and the electrons are weak, and therefore, you have to go to A level stuff to explain.

The main thing they are trying to see, if u can identify that if it is tetrahedral in structure.

I hope that answers ur q.
« Last Edit: March 03, 2010, 04:03:50 pm by The Dude 321 »
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Offline SGVaibhav

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #273 on: March 03, 2010, 04:35:30 pm »
is that diagram for an alloy?? or boron??
wow im back to chemistry after months and it feel good xD  ;D
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holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #274 on: March 04, 2010, 11:10:12 am »
HOLD YOUR HORSES PEOPLE !!!


Everyone is getting confused with what I am asking.... so ill put it here in short:

1.) An alloy is a mixture 2 or more metals. In a diagram for an ALLOY how would you show the mobile electrons ??
2.) Is boron a metal or metalloid ? WHat is its charge ?
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Offline astarmathsandphysics

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #275 on: March 04, 2010, 11:17:15 am »
boron is a Group 13 element that has properties which are borderline between metals and non-metals (semimetallic). It is a semiconductor rather than a metallic conductor. Chemically it is closer to silicon than to aluminium, gallium, indium, and thallium.
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nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #276 on: March 04, 2010, 01:44:44 pm »
Sorry. I've been away for a while

The diff colors r for the diff metals in the alloy. The positive metals ions are in the sea of electrons...similar to metallic bonding but there  metals here do not bond chemically...Alloys r mixtures, not compounds

And boron is a metalloid. It exhibits a +3 charge generally. When bonding covalently it has a 5- charge(e.g. BF3)




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Offline Saladin

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #277 on: March 04, 2010, 03:05:28 pm »
yes nid is right,

wat the examiners want to see is that you have different sizes of atoms, to show there there is more than one element.

But for silicon carbide, it is as I have said.

These answers are for IGCSE and not for A level for higher. So only for IGCSE.

Hope that helps.
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nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #278 on: March 06, 2010, 05:14:50 am »
yup this is IG stuff
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holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #279 on: March 06, 2010, 05:39:22 am »
Yeah... this IG stuff. Got my exmainations in a few weeks time. The clock is ticking *tick* *tock* .... :D ;D
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nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #280 on: March 06, 2010, 05:46:04 am »
Quote from: Ari Ben Canaan on March 06, 2010, 05:39:22 am
Yeah... this IG stuff. Got my exmainations in a few weeks time. The clock is ticking *tick* *tock* .... :D ;D

I have my AS in a few weeks..... :(
Igs is a piece of cake...with a cherry on the top..lol...you'll do well
Good luck! :)
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holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #281 on: March 07, 2010, 11:57:08 am »
Thanks Nid  ;D


I like cherrys
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Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #282 on: March 07, 2010, 03:20:06 pm »
All the best pal.
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holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #283 on: March 10, 2010, 05:21:00 pm »
Question 4) e) all parts.

I dont understand how or why the temperature diff. changes.

Please explain the underlying chemistry concept. What do i need to know to do these kind of questions.


If u have time please see my other post  : https://studentforums.biz/index.php/topic,6204.msg176488.html#new
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holtadit

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #284 on: March 11, 2010, 01:55:14 pm »
Help ?
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