A quick question about valencies (1 Viewer)

[Dragonmaster262]

Do molecules which are made up of the same type of element' such as O2(Oxygen gas)' have the same valency as the individual element? For example does OS, N2 etc have the same valency as O and N respectively?

 

[annabackwards]

We normally write the following:
Just oxygen as an atom = 0^-2 and just nitrogen as an atom = N^-3
Oxygen in its natural state (gas) = 02 and nitrogen in its natural state (gas) = n2

So just from looking at the numbers in the top right hand corner which inicate valencies, i believe that they have different valencies

 

[shady145]

lol was that a typo or did u mean O^-1
coz it O^-2
and it has O valency when O2 as we take the valency of the whole molecule
thats what i think neway

 

[Revacious]

Short answer, no.

Consider the Oxygen radical(O^2-), Oxygen molecule(O2), and the peroxide ion (O2^2-)

As you can plainly see, despite being comprised of only oxygen, the charges are different.


Also consider sulfur, it has many different valencies, as do transition metals; but i think thats beyond the scope of the prelim course?

 

[annabackwards]

lol was that a typo or did u mean O^-1
coz it O^-2
and it has O valency when O2 as we take the valency of the whole molecule
thats what i think neway

Thanks for the pick up, i've edited it ^^

 

[shady145]

lol no worries

 

[Dragonmaster262]

So what are the valencies of O2 AND N2?

Is there any specific way of knowing?

 

[katie tully]

One way to figure it out, and I don't know if you guys do this in the HSC, is to do either a lewis diagram or look at the orbitals (s, p, d, f, etc).

Looking through my old notes to see if I have anything on working out valencies for diatomic molecules.

 

[Hypermelon]

aufbau boxes would help you understand...

 

[katie tully]

This might help.

Atoms will share pairs of electrons so that each has a full outer shell, if possible. This is known as the octet rule, since the outer shell of most of the non-metals can hold at most eight electrons (there are many exceptions, including hydrogen molecule!). The fluorine atom has seven valence electrons. A diatomic fluorine molecule has two atoms and fourteen valence electrons total. If each atom has three electron pairs that it does not share and one electron pair that act as a bond, both atoms fulfill the octet rule (6 free electrons + 2 shared for each atom). The Lewis structure for the fluorine molecule looks like this:

Atoms can share more than one pair of electrons. A single bond is one pair of electrons shared between two atoms. A double bond is two pairs of electrons shared between two atoms. The oxygen atom has six valence electrons, so the diatomic oxygen molecule has two atoms and twelve valence electrons. In order for the oxygen molecule to obey the octet rule, it must have a double bond:

A triple bond is three pairs of electrons shared between two atoms. The nitrogen atom has five valence electrons, so the diatomic nitrogen molecule has two atoms and ten valence electrons. In order for the nitrogen molecule to obey the octet rule, it must have a triple bond:

 

[shady145]

umm arnt any diatomic non metal elements eg H2 O2 N2 all have valencies of zero. or is this for some other rule, i think it was in acidic environment topic. it was with the calculating oxidizing number rules or something. and one of the rules were and molecule like H2 O2 N2 has zero valency

 

[mtsmahia]

I thought molecules didnt have valencies (lol im newb)...i always thought that ions only had valencies.

 

[annabackwards]

umm arnt any diatomic non metal elements eg H2 O2 N2 all have valencies of zero. or is this for some other rule, i think it was in acidic environment topic. it was with the calculating oxidizing number rules or something. and one of the rules were and molecule like H2 O2 N2 has zero valency

Yeah, atoms/molecules in their natual state have an oxidising number of 0

 

[shady145]

Yeah, atoms/molecules in their natual state have an oxidising number of 0

o yea, lol, i havnt done nething for chem in a while.

 

[annabackwards]

o yea, lol, i havnt done nething for chem in a while.

I just got lots of chem shoved down my throat for the last two days... 12 hours of chem in 2 days *shivers*

 

[shady145]

I just got lots of chem shoved down my throat for the last two days... 12 hours of chem in 2 days *shivers*

haha thats what i been doing for english