About compound ions.......

[albertlee]

In my chemistry, it has listed several compound ions, but it does not explain how they are formed and how their charges are found........

 

For eg, NH₄ with 1 positive charge

OH with 1 negative charge

SO₄ with 2 negative charges

HCO₃ with 1 negative charge and so on.....

 

How compund ions are formed, and how their charges are found? according to the formula?

Maybe possible, tell me what kind of property does the formation of compund ions have

 

thx in advance

 

Albert

[Skye]

You can figure out the charge on the compound by the charges (oxidation state) of the atoms that make it up.

 

Example: N^3- is bonded to four H⁺ ions. These add together to give a +1 charge for the compound.

[5614]

heres a good ionic element periodic table, it doesnt show all the elements

it doesn't show the +4 ions for tin and lead. notice the two possible charges for hydrogen. really no ions with such high positive charges exist because too much energy is required to strip off 3 or more electrons.

 

http://misterguch.brinkster.net/ionic.html

now theres a good site on ionoic compounds, ask if you dont understand any of it!

[albertlee]

but 5614, I already know much about ionic compounds....

 

but I want learn more about compound ions.

 

Firstly, I would like to ask, for eg, the compound ions, NH₄, what is the bonding between Nitrogen and Hydrogen in this ion?

 

Albert

[YT2095]

http://scifun.chem.wisc.edu/chemweek/Ammonia/AMMONIA.html

 

http://en.wikipedia.org/wiki/Ammonia

 

http://www.chemguide.co.uk/atoms/bonding/hbond.html

 

and...

 

http://www.historyoftheuniverse.com/ammonia.html

 

some of these may help a little more than just me sitting here and trying to typing it all

[albertlee]

YT, what does hydrogen bonding and ammonia has to do compund ions?

 

I am not familar with hydrogen bonding, it somehow tells that the molecules have charges.....Never know of that, how can molecules have charges? my teacher tells me that compound is neutral for both ionic and molecular....... Any way, confuse...

 

Again, before I go any deeper, I want to know what is the bonding of Nitrogen and Hygrogen in the form of NH₄ ion....

 

Albert

[Firedragon52]

Again, before I go any deeper, I want to know what is the bonding of Nitrogen and Hygrogen in the form of NH_{4[/sub'] ion....}

_{The Nitrogen and Hydrogens are bonded together through covalent bonding. But, the nitrogen, in this case, has a positive charge because it has four sigma bonds where it only wants three sigma bonds.}

 

_{Does that kinda help a little?}

[Skye]

On the hydrogen bonding, the electrons in a molecule or compound aren't even distributed. Some areas tend to have more electrons, other less, at any given moment. This gives these areas a weak charge. This charge is much weaker than the charge due to having a missing/extra electron in the case of ions. Hydrogen bonding is simply a matter of 'opposites attract' between hydrogen atoms (which are slightly positively charged), and parts of other molecules or ions that are slightly negatively charged.

 

(edit: you're right there firedragon, don't nkow what my brain is up to)

[5614]

Again, before I go any deeper, I want to know what is the bonding of Nitrogen and Hygrogen in the form of NH4 ion....

 

YT2095 has already posted a suitable link:

http://en.wikipedia.org/wiki/Ammonia

[albertlee]

but FireDragon, how can Nitrogen in this case take up four sigma bonds?

 

It doesnot make sense...

It is like you make up one ion like this H₃O which has 1 negative charge....

 

By the way, what does "sigma" mean?

 

Albert

[Firedragon52]

but FireDragon, how can Nitrogen in this case take up four sigma bonds?

 

It doesnot make sense...

It is like you make up one ion like this H3O which has 1 negative charge....

I could be wrong, but I think you're asking why would NH3 and H20 form the less stable ions H30+ and NH4+.

 

This is because of the movement of the electron. Sometimes, it will break away from the nucleus of the H and leave a proton H+.

 

The H+ is attracted to the NH3 and H20 because of the molecules 3D arrangement in space and the molecules partial charge.

 

The Molcules have specific orientations in space. This can be shown using a VSEPR model (http://www.molecules.org/VSEPR_table.html).

As you will see in both the...

NH3: http://www.molecules.org/Images/animations/NH3.html

and the

H20: http://www.molecules.org/Images/animations/H2O.html

model, that there is a segment of the central atom not being "occupied".

 

That space is the site of a lone pair of electrons. The water molecule's 3D shape causes it to have form a dipole by the unbalanced electronegativity between the H and the O. So a passing proton (H+) gets sucked into the pretty stable water. The same works for NH3.

 

Did I help?

 

By the way, what does "sigma" mean?

Just a fancy way of saying "single bond". Double and triple bonds are refered to as PI bonds.

http://home.att.net/~cat6a/carb_bonds-I.htm

[albertlee]

This is because of the movement of the electron. Sometimes' date=' it will break away from the nucleus of the H and leave a proton H+.

[/quote']

 

Firedragon, thx for your explanation, but before understand your post, Can any one explain the above quote more clearly? because my chem teacher say you cant break the electrons from an element, otherwise, in this case it will not be hydrogen any more

 

 

Secondly, thx Skye for your explanation, now I know more about Hydrogen Bond, but I have also have two questions for this:

 

According to YT's link:http://www.chemguide.co.uk/atoms/bonding/hbond.html, NH3, H2O and HF tend to have more intermolecular force because they obtain higher boiling point than any other molecules with hydrogen bonding, but how do you determine that? what kind of property in Hydrogen bond tells you there is more intermolecular force?

 

For the second question, since there is hydrogen bond, using the same principle, is there oxygen bond, chlorine bond, etc....?

 

thx for any respond

 

Albert

[5614]

"Can any one explain the above quote more clearly?"

yes, an electron leaves the H and therefore the H become positively charged (more protons then electrons) so its H+

 

"because my chem teacher say you cant break the electrons from an element, "

that is certainly wrong, when there are more or less electrons that is what an ion is.

[albertlee]

5614, I know, but why the electron leaves?

[5614]

ack, gotta run, search 'what causes ionisation' on google, i will post here tomorrow, say so if you have the answer though, im sure someone else will answer, till tomorrow (or whenever)! soz

[albertlee]

There is no ionisation for hydrogen....When an element combines with hydrogen , it is always covalent bonding.... I think FireDragon might mean that share one electron from hydrogen with Nitrogen, then it becomes paritially positive which attracts with lone pair of another NH₃

 

but it does not sound quite right as a formation of a compound ion!!! It is just the intermolecular force that attract every molecule together, and thats all....Nothing much!!! Since NH₃ is valent, there is no need to share with another single hydrogen........

 

So the main question is: How is there an extra hydrogen cobining with NH₃ in any way that makes an ion with a complete positive charge?

 

It is kind of complicated, compound ion is bonded with covalent bonding which produces either complete positive or negative charge that is combined with another ion in ionic bonding.....

 

thx for furthur respond

[budullewraagh]

the hydrogen forms a coordinate covalent bond

[albertlee]

the hydrogen forms a coordinate covalent bond

 

budullewraagh, are you answering my question: How is there an extra hydrogen cobining with NH3 in any way that makes an ion with a complete positive charge?

?

 

what do you mean by "coordinate"?

 

besides that, I know hydrogen always form covalent bond, but again, there is no need for NH₃ to take up one extra hydrogen to share the electrons.......

 

So again again again, How is there an extra hydrogen cobining with NH3 in any way that makes an ion with a complete positive charge?

 

 

thx for the responds

 

Albert

[YT2095]

try this then:

 

Weak base + H2O = conjugate acid + OH-

Most common weak base is NH3

NH3(aq) + H2O(l) = ?

What will K be?

Kb

K = [NH4+][OH-] / [NH3][H2O]

Since water is the solvent, and has a constant concentration

Kb = [NH4+][OH-] / [NH3]

Kb is the base dissociation constant (like Ka)

Kb refers to the equilibrium of the weak base with water to make the conjugate acid and OH-

 

 

taken from: http://66.102.9.104/search?q=cache:k9DhXTEBwa0J:www.southalabama.edu/chemistry/serafin/ch132/lec14.rtf+%22nh3%22+water&hl=en

[Primarygun]

In my chemistry, it has listed several compound ions, but it does not explain how they are formed and how their charges are found........

I think I could help you. I was puzzled in this in my form 3 year.

Although I was not taught to learn that, I found it myself:P

Polyatomic ion consists of covalent bonds.

Just imagine the ammonia molecule, NH3.

If it is given one H one , it should be NH4 , right?

But it is more stable when it lose one electron .

Therefore, it become NH4+.

Ya, I nearly forgot to tell you something which was mentioned by my buddies before.

They are so professional and this web site are professional too, even is the best of the forums. Sometimes, they may think the thing " coordinate covalent" you have learnt.

I am not very powerful so I know the situation you are facing to.

Coordinate covalent bond is a covalent bond.

Take Ozone,O3 , as example.( please find the structure yourself)

One oxygen atom shares one pair to obtain another pair with an oxygen atom.

Then the second oxygen atom gives one pair to share with the thrid one, but the third one doesn't give any to share. Coordinate covalent bond occurs.

[YT2095]

good points made

 

break the NH3 down, H+ is a univalent cation.

and N- is a trivalent Anion.

[Primarygun]

The break produce hydrogen gas?

[YT2095]

well it would yeah, and Nitrogen, but I`m showing How the compound`s formed and Why

[Primarygun]

Thank you. Before your clarifying, my mind was that the break gave a ammonia molecule and one hydrogen ion. I was wrong!

Is that possible? Only one charged particles stay in room?

I think the energy to break to give the hydrogen ion out from that molecule is very large, right?

[YT2095]

it would require alot of energy sure.

 

also rem that Water can act as an acid or a base (amphoteric). and so in the case of the NH3 (a very weak base) the conjugate is shifted, making the OH the Base and the NH4+ the acid.

 

NH3 is Base NH4 is acid