[minneola]

compound: MgF2
If the ionic bonds are broken...

I would think you result in Mg and F2 that are back to the orginal state, not ions and outer shell not filled.

However I am wrong, and I am guessing it has to do with being dissolved in water.

Does water "break" bonds? I thought it merely disolves the compounds in it self, keeping the bond.

What happens?

thanks

[confusedstud]

compound: MgF2
If the ionic bonds are broken...

I would think you result in Mg and F2 that are back to the orginal state, not ions and outer shell not filled.

However I am wrong, and I am guessing it has to do with being dissolved in water.

Does water "break" bonds? I thought it merely disolves the compounds in it self, keeping the bond.


What happens?

thanks

I think it depends. When melting some of the ionic bonds are broken (not all) so there are actually free mobile ions present in the solution though some are not broken but because they are so little, it is still in a liquid or molten state. While when the ionic compound boils all the ionic bonds are broken until it cools down then the cation and anion will recombine. But then again, another reaction can happen which is decomposition. It is almost impossible to tell whether an ionic compound melts first or decomposes first. In decomposition, bonds are broken but when they reform new bonds are created rather than in the melting case whereby the same bonds are reformed. So under the right temperature and pressure either cases can happen.

This is what I remember from reading up the Internet previously. Can someone of a higher level confirm/correct this? Thanks.

[minneola]

Thanks for the response.

This is taken from a practice quiz for my most basic chemistry course, that I just started.

A possible answer is

mg+2 and 2 f+1 will form, either unfilled shells or filled shells. both chemically stable

or "we dont know, as ionic bonds cannot be broken"

or mg and 2 f atoms with filled shells and chemically unstable

thanks!

[confusedstud]

Thanks for the response.

This is taken from a practice quiz for my most basic chemistry course, that I just started.

A possible answer is

mg+2 and 2 f+1 will form, either unfilled shells or filled shells. both chemically stable

or "we dont know, as ionic bonds cannot be broken"

or mg and 2 f atoms with filled shells and chemically unstable

thanks!

Hi, can you type out the possible answers in this format 1)... 2)... And so on because it's difficult to tell what you are trying to say.

In a dissolved case, dissociation occurs - bonds are not really broken but they form a solution where the ions are free to move. When melting occurs and bonds are broken the shells are filled (hence they have their charges) but still, they are separated (element like to be both stable with a duplet or octet structure and also have no net charge) that's why melting is endothermic. For the next art, Ionic bonds can be broken! Magnesium metal (pure) does not have a filled shell if we look at an atom of magnesium there will be two outer shell electrons so it would quickly get oxidised in air (MgO), lastly two fluorine atoms is stable as they share two electrons to achieve a stable duplet structure (covalent bond).

If you are taking a basic chem course and it is only the beginning then you might not fully understand this yet. But I think the question gave should be a simple one. If you write it out properly I can try my best to go though each answer (I'm taking O levels this year so my knowledge should be able to help you).

[discodermolide]

Thanks for the response.

This is taken from a practice quiz for my most basic chemistry course, that I just started.

A possible answer is

mg+2 and 2 f+1 will form, either unfilled shells or filled shells. both chemically stable

or "we dont know, as ionic bonds cannot be broken"

or mg and 2 f atoms with filled shells and chemically unstable

thanks!

Hi, can you type out the possible answers in this format 1)... 2)... And so on because it's difficult to tell what you are trying to say.

In a dissolved case, dissociation occurs - bonds are not really broken but they form a solution where the ions are free to move. When melting occurs and bonds are broken the shells are filled (hence they have their charges) but still, they are separated (element like to be both stable with a duplet or octet structure and also have no net charge) that's why melting is endothermic. For the next art, Ionic bonds can be broken! Magnesium metal (pure) does not have a filled shell if we look at an atom of magnesium there will be two outer shell electrons so it would quickly get oxidised in air (MgO), lastly two fluorine atoms is stable as they share two electrons to achieve a stable duplet structure (covalent bond).

If you are taking a basic chem course and it is only the beginning then you might not fully understand this yet. But I think the question gave should be a simple one. If you write it out properly I can try my best to go though each answer (I'm taking O levels this year so my knowledge should be able to help you).

Melting does not break bonds unless the substance decomposes.
What you are doing during the melting process is breaking up the crystal lattice. Think of ice melting to water, all you are doing is breaking the ice lattice, no chemical bonds cleave.

[confusedstud]

Thanks for the response.

This is taken from a practice quiz for my most basic chemistry course, that I just started.

A possible answer is

mg+2 and 2 f+1 will form, either unfilled shells or filled shells. both chemically stable

or "we dont know, as ionic bonds cannot be broken"

or mg and 2 f atoms with filled shells and chemically unstable

thanks!

Hi, can you type out the possible answers in this format 1)... 2)... And so on because it's difficult to tell what you are trying to say.

In a dissolved case, dissociation occurs - bonds are not really broken but they form a solution where the ions are free to move. When melting occurs and bonds are broken the shells are filled (hence they have their charges) but still, they are separated (element like to be both stable with a duplet or octet structure and also have no net charge) that's why melting is endothermic. For the next art, Ionic bonds can be broken! Magnesium metal (pure) does not have a filled shell if we look at an atom of magnesium there will be two outer shell electrons so it would quickly get oxidised in air (MgO), lastly two fluorine atoms is stable as they share two electrons to achieve a stable duplet structure (covalent bond).

If you are taking a basic chem course and it is only the beginning then you might not fully understand this yet. But I think the question gave should be a simple one. If you write it out properly I can try my best to go though each answer (I'm taking O levels this year so my knowledge should be able to help you).

Melting does not break bonds unless the substance decomposes.
What you are doing during the melting process is breaking up the crystal lattice. Think of ice melting to water, all you are doing is breaking the ice lattice, no chemical bonds cleave.

But in ice the bonds broken are the van der waals forces of attraction. In the ionic compound the bonds within the crystal lattice is the ionic bonds and aren't they actually partially broken?
According to here it is:http://www.enotes.com/chemical-bonds-physical-properties-reference/chemical-bonds-physical-properties

Can you help clear this up for us? Thanks.

[discodermolide]

In water ice melting the Van Der Waals forces break, but not the H-O bonds.
In a crystal lattice you have an ordered array of atoms held together by ionic forces. These break during the melting process, but you still have discrete ionic molecules in the liquid phase.

[confusedstud]

In water ice melting the Van Der Waals forces break, but not the H-O bonds.
In a crystal lattice you have an ordered array of atoms held together by ionic forces. These break during the melting process, but you still have discrete ionic molecules in the liquid phase.

Aren't they ions and not atoms? And by ionic forces do you meant ionic bonds because the attraction between the positive cation and the negative anion is the ionic bond. I don't think that there are any other bonds present in that beside the one that I just mentioned. So this I what I'm thinking - in a molten ionic compound, some (not all) of the ionic bonds are not broken and there are discreet crystals present but as some bonds are broken, there are still free mobile ions present in the ionic compound which allows a current to flow through it. Is this what you are trying to say?

[discodermolide]

In water ice melting the Van Der Waals forces break, but not the H-O bonds.
In a crystal lattice you have an ordered array of atoms held together by ionic forces. These break during the melting process, but you still have discrete ionic molecules in the liquid phase.

Aren't they ions and not atoms? And by ionic forces do you meant ionic bonds because the attraction between the positive cation and the negative anion is the ionic bond. I don't think that there are any other bonds present in that beside the one that I just mentioned. So this I what I'm thinking - in a molten ionic compound, some (not all) of the ionic bonds are not broken and there are discreet crystals present but as some bonds are broken, there are still free mobile ions present in the ionic compound which allows a current to flow through it. Is this what you are trying to say?

Yes.

[minneola]

Here is a better formated question:

Ionic bonds in the compoung MgF2 are broken then you result in:

1. Mg+2 and two F+1 ions, each with unfilled electron shells and chemically stable
2. Mg +2 and two F+1 ions, each with filled electron shells and chemically stable
3. We dont know, ionic bonds cant be broken
4. Mg and two F atoms, each with unfilled electron shells and chemically stable
5. Mg and two F atoms, each with filled electron shells and chemically unstable

Thanks!

I chose #4 and its wrong.

[minneola]

My next guess would be #2


2. Mg +2 and two F+1 ions, each with filled electron shells and chemically stable


Because if the ionic bond is broken then this will result.

However thats not true because #2 is what forms an ionic bond.

Therefore I'm left with "ionic bonds cannot be broken" which MAY be true to my knowledge because the ions formed from ionic bonds (example NACL) arent broken but rather "dissolved" in water.

[confusedstud]

1 and 2 is wrong since flourine has a charge to -1 and not +1. I guess this is indicating that melting has not occurred (when melting Mg2+ ions and F- ions are released they have their shells filled but are nut chemically stable as I said before beside filled shell, they also want to be electrically neutral).3 is wrong as ionic bonds definitely can be broken as what I mentioned earlier.5 is also wrong as pure magnesium does not have a filled shell it has 2 delocalised electrons and fluorine atoms have 7 electrons in their outer most shell.

[Borek]

This is one poorly worded question. I have no idea what they mean by "ionic bonds are broken". Bonds are broken when the ionic substance is melted or dissolved, but the ions don't change (much) during neither process. I don't know for sure what will happen when you heat the MgF₂ with metallic sodium, but the logical outcome is that you end with NaF and metallic Mg - so the ionic bonds were broken, but the Mg is no longer ionic while F^- has not change. When heated in the reducing atmosphere MgF₂ yields MgF (see http://jcp.aip.org/resource/1/jcpsa6/v41/i8/p2250_s1?isAuthorized=no) - so again some ionic bonds are broken, but the outcome is again different and not easy to classify using answers given.