post your Physics and Chemistry querries

[mariam]

chem p5 q2 part (e)??
construction lines mean we have to find the gradient?? :?

 

[beacon_of_light]

construction lines are drawn perpendicular to the point at which the tangent meets the curve of the graph...

 

[beacon_of_light]

it depends on the lone pairs available
just learn that tetrahedral shape has angle 109
piramidal has angle 107
linear shape has 180
trigonal planar has 120
bent shape is 104.5
no more

This is the best approach to bond angels....

And I hope you know the shapes of these molecules as well...

 

[beacon_of_light]

Anymore queries post them....I have got a lot of time today...so i'll answer other queries related to As chemistry ONLY!

how on earth do you have alot of time! we got like no time left and i cant solve any past paper fully and now im freaking out! looks like your prep is good, best of luck with it..
anyways my question is how do you find bond angles? cause all my sir thought us was 120 and 109, i never knew there was a whole range of angles to answer from :s

I just took out time to reply to your posts.That was all! Tomorrow will be very busy so I thought of asking for and giving help.

 

[beacon_of_light]

i dont understand sigma and pi bonds. and how to draw them
for example: O/N 2007 Q1 b.ii) and d)

Now look that is very simple...you need to know a few points...

Sigma bonds are the first bonds formed in a molecule.for example in ethane there are six sigma bonds...while in ethene there are 5 sigma bonds and 1 pi bond.Whereever you see a double bond b/w Carbon atoms, the first bond is ALWAYS sigma and the second bond is ALWAYS pi.

And sigma bonds are formed by the overlapp of any two orbitals, it could be s-s, s-p.

But pi bonds are only formed b/w two p orbitals...px--px, py---py,, .pz---pz...

Sigma bonds have overlapping region in b/w the two nuclie of bonded atoms, while pi bonds are sideways overlapping of p orbitals...

eg.. in ethene molecule sigma bond is a straight line b/w two carbon atoms while for pi bonds, draw to oval orbitals above and below the line of sigma bond...

hope that is sufficient for you....

 

[AE-12]

beacon of light thanks a lot !!!!

 

[beacon_of_light]

you are most welcome!!!

 

[webfactor]

Frankly speaking ...... I was willing to help but beacon of light has played my role.........................

 

[princesszahra]

we all r here to help each other
so keep on ur good job!
and welcome on XPF!

 

[beacon_of_light]

no prob web factor.....I just tried to help..welcome to ur post!!!

 

[beacon_of_light]

sorry i mean to your topic**

 

[1992]

i dont understand sigma and pi bonds. and how to draw them
for example: O/N 2007 Q1 b.ii) and d)

But pi bonds are only formed b/w two p orbitals...px--px, py---py,, .pz---pz...

Sigma bonds have overlapping region in b/w the two nuclie of bonded atoms, while pi bonds are sideways overlapping of p orbitals...

eg.. in ethene molecule sigma bond is a straight line b/w two carbon atoms while for pi bonds, draw to oval orbitals above and below the line of sigma bond...

hope that is sufficient for you....

so how do u draw sigma bonds??
ive understand that PIE bonds are oval, right??
but sigma?? is it just a straght line?? :S

 

[paparazzi]

october 08
2a)i)suggest values for the H-C-H and C=C=O bond angles in ketene?

Now take C as central atom...it has three bonded atoms around it...two are hydrogens and one is CCO....so bond angle is 120*

C=C=O...bond angel is 180* shape is linear///and all linear compounds have linear shape..

Hope that helps u...

it really helps!!!thank u so much....

 

[intel1993]

ya sigma is just a straight line and the circle below and above the staright lines shows pi bond overlapping...................

 

[beacon_of_light]

i dont understand sigma and pi bonds. and how to draw them
for example: O/N 2007 Q1 b.ii) and d)

But pi bonds are only formed b/w two p orbitals...px--px, py---py,, .pz---pz...

Sigma bonds have overlapping region in b/w the two nuclie of bonded atoms, while pi bonds are sideways overlapping of p orbitals...

eg.. in ethene molecule sigma bond is a straight line b/w two carbon atoms while for pi bonds, draw to oval orbitals above and below the line of sigma bond...

hope that is sufficient for you....

so how do u draw sigma bonds??
ive understand that PIE bonds are oval, right??
but sigma?? is it just a straght line?? :S

Well drawing a sigma bond b/w two atoms...it is a straight line ONLY...but if the examiner asks to draw s-orbital..then a roughly spherical round circle should be drawn...

 

[1992]

do u know any site where it can show these 2 types of bonding?? please

 

[mateenyasin1]

wat do you mean by site.................. and wat type of bonding r u talkin abt

 

[mateenyasin1]

Hey !! can anyone tell me why isnt there any change in properties of an atom wen a stray neutron strikes it and then becomes a part of it...........
i kno about the isotope part.. but i dont kno y there isnt any change.........look there is significant change for example the fission process..........

pls help

 

[beacon_of_light]

do u know any site where it can show these 2 types of bonding?? please

here are a few links that may help you.

http://www.brynmawr.edu/Acads/Chem/saved/svpbonds.html

http://www.mhhe.com/physsci/chemistry/a ... m5s2_6.swf

 

[beacon_of_light]

Hey !! can anyone tell me why isnt there any change in properties of an atom wen a stray neutron strikes it and then becomes a part of it...........
i kno about the isotope part.. but i dont kno y there isnt any change.........look there is significant change for example the fission process..........

pls help

The properties of an atom, both physical and chemical, depend on the number of electrons since they take part in bonding. In the example that you provided, there is a change in the composition of nucleus but the no of electrons remain the same. So there isn't any change in an atom's property...