electrone

[TimbaLanD]

when Na+ combines with Cl-, we get NaCl. Which orbit does the electrone take? Na or Cl?

[RyanJ]

when Na+ combines with Cl-, we get NaCl. Which orbit does the electrone take? Na or Cl?

 

I do not understand your question...

 

The [ce]Cl^{-}[/ce] ion "shares" its extra electron with the sodium, they are pulled together by electrostatic attraction... Basically we hyave this: [ce]Na^{+}Cl^{-}[/ce] but as the charges are actually equal, they counter act one and other so we write just NaCl. This is a type of ionic, I do not believ eletrons are actually transfered one way or another...

 

Can you re-phrase your question please?

 

Cheers,

 

Ryan Jones

[TimbaLanD]

Ok, well basically "Na" has one electrone on the outer shell and "Cl" has 7 electrons on the outer shell. When "Na" is on its own, its electrone orbits around its nucleus but when it loses its electroen to "Cl", does this mean the lost electrone will never ever take an orbit around "Na" even though they form a compound? Have i confused you even more?

[RyanJ]

Ok, well basically "Na" has one electrone on the outer shell and "Cl" has 7 electrons on the outer shell. When "Na" is on its own, its electrone orbits around its nucleus but when it loses its electroen to "Cl", does this mean the lost electrone will never ever take an orbit around "Na" even though they form a compound? Have i confused you even more?

 

I think I undertstand. OK yes you are correct, Sodium wants to attain a more stable state by loosing its outer s-shell electron and chlorine wants one more so it takes this electron.

 

Think of it this way, all reaction involve a movement of electrons, in this case from the Na to the Cl - they are more stable with a complete electron shell so they like to stay that way. How ever the nature of the ions means that they will attract one and other and form a strong ionic bond, thats why its so hard to melt salt. The Na can re-gain its electron but it does not readily do this because it "likes" its more stable state. If you say added potassium to a solution of falt you would get potassium chloride and sodium (not for long though as it would react very fast).

 

Did that help at all?

 

Cheers,

 

Ryan Jones

[woelen]

There are two types of extremes, when we are talking about chemical bonds.

One type is the so-called covalent bond, where electrons are shared between (usually) 2 atoms. An example is Cl2. Both Cl-atoms are 'missing' one electron. Both of them 'donate' one electron and they share the two 'donated' electrons. That makes them both happy, because they now both have a full set of electrons.

The other type is the so-called ionic bond, where electrons are not shared, but really transferred. An example is NaCl. Na has one surplus electron and wants to get rid of this. Chlorine wants another electron. Both elements are happy if this electron is transferred. Na gives it to Cl. Na becomes an ion Na(+) and Cl also becomes an ion Cl(-). The total compound now consists of ions in a 1 : 1 ratio. A better formula for salt hence would be Na(+)Cl(-) instead of NaCl.

 

In the real world, however, the two extremes are quite uncommon. Cl2 and NaCl are two extremes, but most compounds, consisting of different atoms are somewhere inbetween. The atoms share electrons to some extent, but the sharing is not equal. E.g. in H2O, each H shares its single electron with an electron from an O. In this way, each H has two electrons and each O has 8 electrons in its outer shell. However, the O atom shares it a little bit more than the H-atoms, so in water, there is a slight negative charge on the O and a slight positive charge on the H, so the real structure is H(δ+)O(2δ-)H(δ+), with δ < 1, but definitely larger than 0.

 

In general, for compounds, atoms have a charge nδ (here n is the formal oxidation state of the element, e.g. -2 for oxygen, +3 for aluminium, +2 for calcium). The closer δ is to zero, the more covalent a compound is, the closer it is to 1, the more ionic it is.

 

Some examples:

 

Na(δ+)Cl(δ-) : NaCl, almost purely ionic, δ very close to 1

Ca(2δ+)O(2δ-) : CaO, almost purely ionic, δ very close to 1

Cr(6δ+)O(2δ-)O(2δ-)O(2δ-) : CrO3, δ very close to 0, almost purely covalent

 

Compounds like Fe2O3, Cr2O3 and Al2O3, MnO2 are very much inbetween. Their δ is not close to 1, but also quite far from 0. Hence, they are intermediate and one cannot call them purely covalent, but also not purely ionic.

 

========================================================================

 

In many compounds, both types of bonds occur at the same time. Inside the compound KNO3, for example we have K(δ+) and NO3(δ-), with δ very close to 1. This means that the compound KNO3 is almost purely ionic. But, inside the unit NO3(-), the atoms are bound almost purely covalently. So, we have ions K(+) and NO3(-), but NO3(-) itself can be regarded as a covalent molecule, but now with a total charge on this molecule, equal to -1.

When we look at the compound HNO3, then the whole molecule can be regarded as covalent, but with a fairly large δ+ at the H-atom.

 

In the nitrate ion, however, the electrons are not simply shared between two atoms, but the total set of electrons, available for bonding is shared over all atoms. As I stated at the beginning of this post, electrons usually are shared between two atoms, but they can be shared between more atoms. In the nitrate ions (and in fact in many other ions and molecules) this is the case. Another example of such a situation with more electrons shared by multiple atoms is benzene, where 6 electrons are shared by 6 C-atoms. This type of covalent bonds over multiple atoms is called 'delocalized bonding'.

[TimbaLanD]

wow! i need to understand this before coming back with queries!! I guess my original query was, when 2 atoms (A & B) share an electrone, which orbit does the electrone follow? A or B?

[RyanJ]

wow! i need to understand this before coming back with queries!! I guess my original query was, when 2 atoms (A & B) share an electrone, which orbit does the electrone follow? A or B?

 

Depends, the elctron normally is "pulled" more towards the most electronegative element, in this case its complety pulled away from the sodium forming a nodium ion. As Woelen pointed out this is the latter of the two extemes, this is where the difference in electronegativity is high enough for the electron to actually become detatched from one ion and is pulled too the more electonegative element.

 

So the answer to your question, if I understand what your asking, if chlorine and in general it "moves closer too" the more electronegative element

 

If your interested the following links may help you understand...

 

http://www.chemguide.co.uk/atoms/bonding/ionic.html#top

 

http://www.chemguide.co.uk/atoms/bondingmenu.html#top (In general)

 

Cheers,

 

Ryan Jones

[Yggdrasil]

wow! i need to understand this before coming back with queries!! I guess my original query was, when 2 atoms (A & B) share an electrone, which orbit does the electrone follow? A or B?

 

When two atoms (A and B) share electrons in a covalent bond, the electrons are neither in A's atomic orbitals nor are they in B's atomic orbitals. The atomic orbitals of A and B merge to form molecular orbitals which are combinations of the atomic orbitals of A and B. The shared electrons reside in these molecular orbitals. For example, when you look at the molecular orbitals of water you can see that they do not resemble the atomic orbitals of hydrogen or oxygen.

[TimbaLanD]

I see.. so basically the shared electron is fixed in position almost like it has been clamped. But when “Na” loses its electron to “CL”, the “Na” atom is held together by that single electron so basically it dangles from this single electron. I am so getting interested in the electron configuration of atoms. It’s amazing to think that shifting a few electrons can change the physical appearance!!

[woelen]

Yes, that is the main point of chemistry. A shift of a single electron can make a whole lot of a difference. The properties of all chemical compounds around us are determined by the electronic configuration around the nuclei. The nuclei themselves do not interact in any way in chemical reactions and also do not contribute in any way to the physical properties, other than mass, of the chemical compounds.

 

The molecular orbital's shape goes from fully distributed over all atoms in a purely covalent bond to fully around one atom in a purely ionic bond.