Which of the following contains an sp2-hybridized carbon?

CH4
CH3-
CH3CH3
CH3+
HC(triple bond)CH

Best Answer - Chosen by Voters
It is CH3+
There are 3 pairs of electrons around the carbon atom.
This suits the sp2 hybridised orbitals of carbon and it will take the shape of trigonal planar.

CH3- is not sp2 hybridised.
It is sp3 hybridised.
There are 4 pairs of electrons around the carbon atom.

Although it is sp3 hybridised, the shape is trigonal pyramidal because there is a lone pair of electrons.

DOT AND CROSS DIAGRAM

How do you draw the dot and cross diagrams for:?
Aluminium oxide
Carbon Tetrachloride
andSulfur dioxide?

Best Answer - Chosen by Asker

Aluminium oxide is an ionic compound. So, there is a complete transfer of electrons from aluminium to oxygen atom.

In aluminium oxide ( Al2O3), each atom of Al will transfer three electrons to the oxygen atoms. So, the two Al atoms will transfer a total of six electrons to the three oxygen atoms (each oxygen atom will receive two electrons).

[: Al :]^3+ [ O ]^2-

{All togather there are eight dots around Al and O is surrounded by six cross and two dots. Dots are electrons from Al and crosses are electrons of O}

For carbon tetrachloride, CCl4, Write the C at the centre and is surrounded by four Cl. Between each of the C and Cl is placed a dot and a cross.

Then, six dots around each of the Cl atom.For sulphur dioxide,

SO2, Write the S at the centre and the two O on each side ( in 'V' shaped).
Put two dots and two crosses between S and O.
Then another two dots for S.
Lastly, put four crosses around each O. [ You will fine that there are ten electrons around S.
This is possible because of the expansion of octet]


Asker's Comment:
I managed to get Aluminium oxide and Carbon Tetrachloride before you replied, but I forgot about the expansion of octet and it was troubling me when I went to sleep :)Thanks for your description, I'll do the SO2 as you say it (in my original answer I left the last O atom with only 6 electrons).

VSEPR THEORY

For the rules of VSEPR - predicting shapes of molecular compounds.. please help with question below?

a) predict shape of molecular orbitals around central atom and give the angle/s between orbitals of GeH4, PCl5, SF6 (all numbers are the little numbers on the bottom (not top))

b) predict the shape of the molecular orbitals around the central atom and explore the shape of the actual molecule - give the change in the angle size and reason for itif anyone could please help assist answering this question or any part of it that would be AWESOME


by joeyeehu...

Best Answer - Chosen by Voters
In VSEPR theory, the electron pairs will be placed as far apart as possible to reduce repulsion.

GeH4:
Ge = 4e
4H = 4e
Total = 8e

= 4 electron pairs

The shape is tetrahedral with a bond angle of 109.5 degree

P = 5e
5Cl = 5e
Total = 10e = 5 electron pairs
The shape is trigonal bipyramidal. It has two types of bond angles: 90 and 120 degree

S = 6e
6F = 6e
Total = 12 e = 6 electron pairs
The shape is octahedral with bond angles 90 degree.

LEWIS STRUCTURE AND SHAPE

What is the best lewis structure of CLF2+?

Best Answer - Chosen by Voters

First, calculate the total number of electrons around the central atom,
that is Cl.

Cl - 7e
2F - 2e ( F is the terminal atom, so each atom will contribute one electron )

The total is 8e as you have to minus one electron because of the one positive charge.
So, there are 8 electrons around the central atom Cl. ( 4 electron pairs)

The 4 electron pairs will be placed as far apart as possible around the Cl atom.
Tetrahedral arrangement is the most likely geometry.

Out of the 4 electron pairs, 2 of them will be the bond pairs ( forming bonds with F in Cl-F) and the other 2 will be the lone pairs.

Hence, the Cl atom will be surrounded by 2 lone pairs and 2 bond pairs of electrons and it will take the shape of 'V' or bent.

The Lewis structure: [:F- Cl - F:]+

* There will be two dots each at the bottom and above the F-Cl-F
* For your information, F can only form one bond.

STOICHIOMETRIC PROBLEM

Magnesium reaction can you solve it?

12g of Magnesium reacts with an excess off dilute sulfuric acid. Calculate the volume of gas produced at 25 degrees celcius and 100kPa.

by joeyeehu...

Best Answer - Chosen by Voters

Mg + H2SO4 -----------> MgSO4 + H2

24g of Mg will produce 1 mol of H2

12g of Mg will produce 0.5 mol of H2

Applying ideal gas law,

PV = nRTV = (0.5 x 8.31 x 298 ) / 100 x 1000... = 1.24 x 10^-2 m3

ISOTOPIC AND ATOMIC MASS

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Difference between relative ISOTOPIC mass and relative ATOMIC mass?

Can anyone tell me is there any difference between relative ISOTOPIC mass and relative ATOMIC mass???
In my class they are introduced separately, but it seems like they are same when I read some other textbooks/reference.
Besides difference, how are they similar to each other??
Please don't copy the paragraphs in Wikipedia "Atomic Mass".........Thanks.

so, do they refer to the same thing or just different??and... what is RIM?

by joeyeehu...
Member since:
15 July 2006
Total points:

Best Answer - Chosen by Voters
Most natural occurring elements can exist in a few isotopic form. Some has two, some has three and some has six ....ect.For example, chlorine can exist as two isotopic forms, namely chlorine-35 and chlorine-37.

We can say that the relative isotopic mass of chlorine-35 is 35 and the relative isotopic mass of chlorine-37 is 37.

To determine the relative atomic mass of chlorine, then you must know the relative abundance of isotope Cl-35 and that of isotope Cl-37. It is found that the relative abundances of Cl-35 and Cl-37 are 75% and 25%.

The relative atomic mass of Cl is the weighted average of the relative isotopic mass of Cl-35 (75%) and the relative isotopic mass of Cl-37 (25%).

So, relative atomic mass of chlorine ={ (75 x 35) + (25 x 37) } / 100..............................… 35.5

So, RIM of element X refers to the relative mass of a particular isotope only.

RAM of element X refers to the average relative mass of all isotopes of X.


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