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Offline NTP

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Oxides
« on: July 23, 2006, 06:14:40 AM »
Hi,


Heres the Question:
Oxides of the second Period Include:
BO3
N2O5
N2O3
CO2
Li2O


I checked the answer and it says that the incorrect of all these is B03 . I don't know why this is so since in the question it wasn't defined if the oxide of the second period is acidic or basic. Could be cos Boron is a semi-metal but I can't understand why BO3 is the incoreect one and not the others. Can someone kindly please explain this to me.
Thank you in advance!
NTP

Offline billnotgatez

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Re: Oxides
« Reply #1 on: July 23, 2006, 06:46:31 AM »
Balance

This is a trick question



Li +1 -7
Be +2 -6
B  +3 -5
C  +4 -4
N  -3 +5
O  -2 +6
F  -1 +7
Ne   0


N2O3 is perplexing




« Last Edit: July 23, 2006, 07:38:49 AM by billnotgatez »

Offline NTP

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Re: Oxides
« Reply #2 on: July 23, 2006, 08:30:09 AM »


But why BO3 is not an oxide then??

Offline billnotgatez

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Re: Oxides
« Reply #3 on: July 23, 2006, 08:39:35 AM »
Which of these are most likely
BO
BO3
BO2
B3O2
B2O3
B3O3
B2O2
B2O





Offline NTP

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Re: Oxides
« Reply #4 on: July 23, 2006, 11:08:25 AM »


BO2 maybe not sure but

Offline billnotgatez

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Re: Oxides
« Reply #5 on: July 23, 2006, 11:36:08 AM »
Quote
BO2 maybe not sure but

Nope

Why is it H2O and not H10O ?

Why did I put that list of elements down and numbers beside them?

There are certain concepts on how compounds are formed. At one time I learned the octet rule which may be passe today. Certainly the N2O3 compound is not likely to be explained by the octet rule. So the original question was double tricky.


« Last Edit: July 23, 2006, 11:44:59 AM by billnotgatez »

Offline Donaldson Tan

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Re: Oxides
« Reply #6 on: July 23, 2006, 06:04:26 PM »
But why BO3 is not an oxide then??

Balance

This is a trick question

BO3 don't exist, that's why it is an invalid choice.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline wereworm73

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Re: Oxides
« Reply #7 on: July 23, 2006, 09:33:43 PM »
There's no way you can have a neutral, uncharged molecule for "BO3".  Each oxygen atom wants to take a pair of electrons in order to fill its electron shell, and since you're dealing with 3 oxygens, this would be a total of 6 electrons.  However, one boron atom can only give up 3 valence electrons.  So, you're going to need 2 boron atoms for every 3 oxygens, and the resulting molecule would be B2O3.

Offline billnotgatez

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Re: Oxides
« Reply #8 on: July 23, 2006, 09:53:30 PM »
Somebody want to explain N2O3

Offline wereworm73

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Re: Oxides
« Reply #9 on: July 24, 2006, 12:04:46 AM »
Alrighty then.  Nitrogen has 5 valence electrons, though it doesn't necessarily give away all of them.  With N2O3, the nitrogen atoms only give away 3 electrons each.
     ..     ..
O=N-O-N=O

This compound isn't very stable, though, and the nitrogens would actually prefer to completely empty their shells (in the presence of highly electronegative atoms like oxygen or fluorine) than partially empty them.  If N2O3 is dissolved in water long enough, a nitrogen can give away its remaining two electrons to an oxygen to form a nitrate ion (as nitric acid), along with some nitric oxide gas (though not in just one step--the N2O3 breaks down into NO & NO2 first).

The nitric oxide, incidentally, also has some valence electrons left and will lend them to oxygens when given the chance.   

Offline NTP

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Re: Oxides
« Reply #10 on: July 24, 2006, 04:59:45 AM »
Thanks all for the help  ;)


I have a similar question to this one which says this:

Oxides of the Third Period include:
Na2O
MgO2
Al2O3
SiO2
Cl2O7


So in this case it is MgO2 is the incorrect one because Mg = +2 and O = -2 therefore should be Mg2O2 right?
While the others are correct since:
Na = +1, O = -2  therefore Na2O
Al = +3,  O = -2  therefore Al2O3
Cl = -1, +1, -3, -5, -7, 0 = -2, therefore Cl2O7

SiO2 is a bit hard because Si has a valency of 4 since it is a element in group 4 so how come it is SiO2 and Not Si2O4?
So which one is wrong SiO2 or MgO2? I say MgO2 but not sure why

Offline Albert

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Re: Oxides
« Reply #11 on: July 24, 2006, 05:08:53 AM »
Yes, MgO2 is wrong. It's just a simple maths problem, up to a certain point: SiO2 is correct because, given that O = -2 and Si = +4 (in this case), considering 1 atom of silicon, you'll need 2 atoms of oxygen for balancing the charges.

On the other hand, MgO2 is incorrect, as you pointed out. However, it should be MgO: 2 positives charges v. 2 negative charges. That's it. Who asked for four ones?  ;)

Offline billnotgatez

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Re: Oxides
« Reply #12 on: July 24, 2006, 08:48:45 PM »

Li +1 -7
Be +2 -6
B  +3 -5
C  +4 -4
N  -3 +5
O  -2 +6
F  -1 +7
Ne   0
Na +1 -7
Mg +2 -6
Al +3 -5
Si +4 -4
P  -3 +5
S  -2 +6
Cl -1 +7
Ar   0

Offline NTP

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Re: Oxides
« Reply #13 on: July 25, 2006, 11:42:03 AM »


Thanks all for your help  ;)

Offline billnotgatez

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Re: Oxides
« Reply #14 on: July 25, 2006, 08:30:53 PM »
Quote
Cl = -1, +1, -3, -5, -7, 0 = -2, therefore Cl2O7

I am not sure your reasoning is correct, but Cl2O7 seems to be a valid compound

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