nitrite and nitrogen dioxide (1 Viewer)

[crammy90]

one is NO2 and the other is NO2-. what makes one an ion and the other a molecule?

 

[crammy90]

I don't get what you're saying, but nitrogen dioxide is a molecule, nitrite is an ion.
One has no overall charge (molecule), the other has a net charge (-1) (ion).

???

lol but how can something exist as an ion and then just as a molecular compound
like i understand it for say an element like Ag can be Ag or Ag+. but how can a molecule be both?

 

[Pwnage101]

lol u know there also exists the nitronium ion ( NO2+) - all 3 have same molecular formula

its all about the electrons, take a careful look at the Lewis Electron dot structures:

nitrogen dioxide: http://www.madsci.org/posts/archives/2000-02/951452623.Ch.2.gif (see how 1 O has 5 e, the other 4)

nitrite: http://z.about.com/d/chemistry/1/0/T/W/lewisnitrite.jpg (see how 1 O has 4 e, the other 6)

 

[syriangabsta]

what the heck...lol

just memorise stuff, loll, even if u dont get it coz i sure as heck dunno what you're going on about

 

[Pwnage101]

wat he's askin is legit, how can somehing have same molecular formula, different charge - and as i said, its all about the electrons - the protons will give u the type of atom it is (ie the element), so the nuclei that make up the atoms in the molecules of all 3 aforementions NO2's is the same, but there is a different number of electrons.....

 

[crammy90]

wat he's askin is legit, how can somehing have same molecular formula, different charge - and as i said, its all about the electrons - the protons will give u the type of atom it is (ie the element), so the nuclei that make up the atoms in the molecules of all 3 aforementions NO2's is the same, but there is a different number of electrons.....

ah k yeh thanks heaps so its to do with the electrons kool
so in nitrogen dioxide if we look at the dot lewis example "http://www.madsci.org/posts/archives/2000-02/951452623.Ch.2.gif" (using the molecule on the right) we see the O to the bottom left has brought 6 e's and attached to the N which has 7 (gained 2 from the other O). When they covalently bond in the single covalent bond the N ends up with 8 (7 + 1 from the new O) and the oxygen recieves 1 from the N to end with 7 e's. This is not an outter shell and i dont see why this O would join in when it isnt going to receive a full shell??? isnt that the point of bonding and why some cant bond with others as they must recieve a full outter shell from it?

 

[brenton1987]

This is not an outter shell and i dont see why this O would join in when it isnt going to receive a full shell??? isnt that the point of bonding and why some cant bond with others as they must recieve a full outter shell from it?

Nitrogen dioxide can only be formed by the oxidation of nitric oxide, NO.

The lewis structure for the free atoms has a nitrogen with five electrons of which three are unpaired and an oxygen with six electrons of which two are unpaired. When a molecule of NO is produced a double bond forms leaving nitrogen with a single unpaired electon

Now if that molecule is oxidised the atoms present are nitrogen with five electrons of which three are unpaired and two oxygen atoms with six electrons of which two are unpaired. An unpaired electron on each oxygen binds to the nitrogen through an unpaired electron. Now there is a single unpaired electron on each oxygen and nitrogen atom.

The second bond between nitrogen and oxygen will continually switch between the nitrogen oxygen bond pairs. This constant rearrangement of the double bond is call resonance stability. Because the bond is never isolated between a single pair of atoms the stability of the molecule increases. Secondly two molecules of nitrogen dioxide can dimerise through the unpaired electron to form dinitrogen tetroxide which contains no unpaired electrons.

Resonance stability and dimerisation result in an increase in stability in the nitrogen dioxide molecule which explains it formation from nitric oxide.

 

[crammy90]

haha i drew it but yeh
i dont quiet undersand this?

 

[syriangabsta]

haha i drew it but yeh
i dont quiet undersand this?

what the...are they both typos? :S

 

[brenton1987]

haha i drew it but yeh
i dont quiet undersand this?

The first picture is correct but you've labelled the paired electrons as unpaired. The unpaired electrons are used in bonding but the pairs are not.

Where 1 shows the free atoms and 2 and 3 show the molecule.

Your second picture shows an unpaired electron on nitrogen and a single electron pair on oxygen with a quadruple bond between the two atoms.

I see where you became confused

The lewis structure for NO has a nitrogen with five electrons of which three are unpaired and an oxygen with six electrons of which two are unpaired. When the molecule is produced a double bond forms leaving nitrogen with a single unpaired electon

This part wasnt written properly

It should have been:
The lewis structure for the free atoms has a nitrogen with five electrons of which three are unpaired and an oxygen with six electrons of which two are unpaired. When a molecule of NO is produced a double bond forms leaving nitrogen with a single unpaired electon

 

[crammy90]

i see
i didnt quiet get it aha now i do. I didnt realise paired electrons could be from the same atom i.e. oxygen has 6 electrons and 3 pairs, no unpaired; Nitrogen has 5 electrons, 1 unpaired electron and 4 paired. So yeh.
i was looking at it as if even though the oxygen has the 2 pairs of electrons, i thought they were unpaired as they werent in a bond or shared aha.

and from ur diagram i see that the unpaired electron from N goes over in the double covalent bond so now N has donated 3 electrons and O 1. Is there a name for this bonding? where one donates more than another. Like i know coordinate covalent is when one species provides BOTH electrons. Here O provides one seemingly.

So we have currently in our NO : O with one unpaired electron and N with no unpaired but only 6 in its outer shell.

Now if that molecule is oxidised the atoms now present are nitrogen with five electrons of which three are unpaired and two oxygen atoms with six electrons of which two are unpaired. An unpaired electron on each oxygen binds to the nitrogen through an unpaired electron. Now there is a single unpaired electron on each oxygen and nitrogen atom. A second bond can form between an oxygen and the nitrogen leaving a single unpaired electron on the other oxygen atom.

i understand it aha yay
cant believe it took me this long to know what an unpaired electron was aha
when we draw O in class its always three pairs of electrons and so i thought it had to loose an electron to have an unpaired electron.

so for a coordinate covalent bond for this syllabus using oxygen:


is that all right?
what in a covalent bond has one species has provided the electron pair for the bond, what separates it from being ionic as in ionic they donate electron pairs :S
or is it just because ion is metal + non metal and coordinate covalent is like an ionic bond for non-metal + non-metals
and lastly: how do u know if an elements/compounds electrons are paired. Like when i was drawing Mg i realised i didnt know whether to put them together or not..
lol and what causes the extra O in ozone to be attracted to the stable O2

aha sorry for all my questions:
just thought id post them in one post instead of multiples and you having to come back
and ive tried researching before asking you theses lol

 

[brenton1987]

where one donates more than another. Like i know coordinate covalent is when one species provides BOTH electrons. Here O provides one seemingly.

Because it is a double bond there is one single bond and one coordinate covalent single bond.

Oxidising nitric acid (2 and 3) produces nitrogen dioxide (5).

It can be seen that nitrogen contains a set of seven electrons as three bonds and an unpaired electron that causes dimerisation. The blue and purple oxygens alternate between containing a full set of eight electrons as two pairs and two bonds and eight electrons as three pairs and one bond.

so for a coordinate covalent bond for this syllabus using oxygen:
is that all right?

The part about unpaired electrons floating around is incorrect. They would form an electron pair because there are only four available orbitals in oxygen. (Reasoning is part of aufbau and pauli below).
The second bond in the double bond becomes resonant due to the bond number of the oxygens. You could almost think of it as one and half bonds between the oxygens. At any moment in time the second bond could be between either oxygen pair.

what in a covalent bond has one species has provided the electron pair for the bond, what separates it from being ionic as in ionic they donate electron pairs :S
or is it just because ion is metal + non metal and coordinate covalent is like an ionic bond for non-metal + non-metals

The bond is not ionic because when the atoms separate the electrons arent left behind. They go back with their original atom.

and lastly: how do u know if an elements/compounds electrons are paired. Like when i was drawing Mg i realised i didnt know whether to put them together or not..

It is based on the Aufbau Principle and Pauli Exclusion Principle as well as others.

lol and what causes the extra O in ozone to be attracted to the stable O2

Ozone is much less stable than oxygen so it isnt really attracted at all. Ozone will spontaneously decompose to oxygen but it wont spontaneously form. It takes high energy UV radiation and lightning to create it.

I hope this makes it less confusing instead of more confusing. There really is no way to go into it without going way outside HSC level. Search online for a university level textbook and read the chapter on Atomic Structure. Make sure it includes quantum mechanics and the hydrogen atom, the pauli exclusion principle and the periodic table.
That will explain why an oxygen atom has two electron pairs and two unpaired electrons instead of three electron pairs and coordinate covalent bonding among others.

 

[crammy90]

thanks heaps you were heaps of help
it doesnt make it confusing it made it easier. Well the wikipedia links were confusing so i sorta read only the first paragraphs of each to get the idea. Atleast i know that there are things to explain it that i havent learnt. I thought i should have known it but i doubt i need to know it for HSC
u gave me everything at the level i need it for HSC im pretty sure