# chemistry question

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#1
can anyone explain why carbon dioxide has the formula CO2.....i know its got something to do with Carbon having a combining power of 4 and Oxygen of 6....but can anyone explain it properly? Thanks
0
15 years ago
#2
oxygen has a valency of 2, so an O atom likes to have 2 bonds
carbon has a valency of 4, so it likes to have 4 bonds (which occur by having 2 double bonds)

something like that
0
15 years ago
#3
(Original post by hihihihi)
oxygen has a valency of 2, so an O2 atom likes to have 2 bonds
carbon has a valency of 4, so it likes to have 4 bonds (which occur by having 2 double bonds)

something like that
O2 isnt an atom.

Oxygen has valency 2, so needs to form 2 bonds, carbon has valency 4, so wants 4 bonds. Each oxygen can provide 2 bonds, so the carbon bonds with 2 oxygens to make 2x2 = 4 bonds.
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15 years ago
#4
There are double bonds, so all four of the carbon's outer electrons are used in bonding, two for each oxygen. This fills up both the carbon's and oxygen's outer shells.
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#5
Thanks guys! I appreciate it
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15 years ago
#6
(Original post by mik1a)
There are double bonds, so all four of the carbon's outer electrons are used in bonding, two for each oxygen. This fills up both the carbon's and oxygen's outer shells.
aren't they called double ionic bonds?

the whole period and group thing on the periodic table tells you how many electrons they have on their outer shell and their valency as well, I think...

Hang on I can't remember!
0
15 years ago
#7
(Original post by me!)

aren't they called double ionic bonds?

the whole period and group thing on the periodic table tells you how many electrons they have on their outer shell and their valency as well, I think...

Hang on I can't remember!
No, they are double covelant bonds - each atoms donates two electrons to the bond. Ionic bonds... well, imagine magnesium and oxygen. Think of it as a "double covelant bond", but where magnesium holds onto all 4 "shared" electrons because the force between the Mg2- ion and the 4 electrons is MUCH stronger than the force between the O2- ion and the 4 electrons. There is a scale, dependant on the charachteristics of each atom, of where the shared pair spend most of their time - pure covelant means they are, on average, in the centre of the bond. Pure ionic means they orbit the cation all the time, because the cation can attract them so strongly.

But for GCSE just remember metals and non-metals means ionic, and non-metals and non-metals are covelant... don't get confused.
0
15 years ago
#8
(Original post by mik1a)
No, they are double covelant bonds - each atoms donates two electrons to the bond. Ionic bonds... well, imagine magnesium and oxygen. Think of it as a "double covelant bond", but where magnesium holds onto all 4 "shared" electrons because the force between the Mg2- ion and the 4 electrons is MUCH stronger than the force between the O2- ion and the 4 electrons. There is a scale, dependant on the charachteristics of each atom, of where the shared pair spend most of their time - pure covelant means they are, on average, in the centre of the bond. Pure ionic means they orbit the cation all the time, because the cation can attract them so strongly.

But for GCSE just remember metals and non-metals means ionic, and non-metals and non-metals are covelant... don't get confused.
It's months since I've done this :/ I've got my chemistry exam on Monday, yay for last minute revision!

Thanks btw
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