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Topic: Directional vs non-directional bonding...  (Read 50070 times)

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Byrne

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Directional vs non-directional bonding...
« on: January 29, 2006, 01:39:55 PM »
I've spent some time looking for information on the internet, but all of the sites I come across simply use the terms and do not explain exactly what they mean.  

Another things that is confusing me, my text says that ionic crystals are formed by a 3-D arrangement of positive and negative ions held together by strong, directional bonds, while the information I've found on the net claims that ionic bonds are non directional  ???

So what 's the difference between these types of bonding and is directional or non directional bonding present in ionic crystals?

Offline Donaldson Tan

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Re:Directional vs non-directional bonding...
« Reply #1 on: January 29, 2006, 03:00:13 PM »
Ionic bonds involves the electrostatic attraction between opposite-charged ions. imagine a stationery positive charge. when a negative charge is placed in the vincity of the positive charge, there will be attraction between the 2 opposite charged ions. there will be attraction regardless the position of the negative. Hence, ionic bonds are said to be non directional.

In the case of covalent bonds, the bonding electron pair must be between the 2 bonding nuclei. In this sense, the position of the bonding electron pair decides the direction of the covalent bonding.

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Byrne

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Re:Directional vs non-directional bonding...
« Reply #2 on: January 29, 2006, 03:06:26 PM »
Does the arrangement of ions in a crystal lattice account for the directional bonding in ionic crystals?

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Re:Directional vs non-directional bonding...
« Reply #3 on: January 29, 2006, 03:31:38 PM »
there is no directional bonding between ions inside an ionic lattice.

however, ionic lattic can exhibit directional bonding in a non-direct manner. such directional bonding arises through intramolecular covalent bonds. Eg. there is directional bonding between Nitrogen and Oxygen in the NO3- ion.
« Last Edit: January 29, 2006, 03:32:27 PM by geodome »
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Byrne

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Re:Directional vs non-directional bonding...
« Reply #4 on: January 29, 2006, 08:16:37 PM »
Without directional bonding, how can you explain the property of ionic crystals that, when struck with a sharp blow, the crystal will fall apart?

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Re:Directional vs non-directional bonding...
« Reply #5 on: January 31, 2006, 09:32:12 AM »
The strike displaces the layers within the ionic lattice such that the like-charged ions in adjacent layers are facing each other. This results in repulsion, thus ionic crystal will break.

If directional bonding exists, a strike would not able to displace the ionic lattice.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

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