Arranging Compounds by Increasing Lattice Energy

In summary, the order of increasing lattice energy for the given compounds is BaTe, Rb2Se, KCl, AlN. This is because the product of charges is higher in BaTe and the sum of ionic radii are relatively similar, resulting in a higher lattice energy. The use of the equation L.E. = k (product of charges)/(sum of ionic radii) can be helpful in calculating the relative lattice energy.
  • #1
physstudent1
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Homework Statement



Order the following compounds in order of increasing lattice energy:

AlN, BaTe, KCl, Rb2Se

Homework Equations


The Attempt at a Solution


Ok I know that as the distance between the two nuclei decreases and as the charge of the cation and anion increase the lattice energy increases, so I thought the order would be

KCl, BaTe, Rb2Se, AlN however this is wrong...I'm not sure why but I think the Rb2Se is confusing me anyway I would appreciate it if someone could help me out here
 
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  • #2
i think lattice energy of BaTe is higer than that of Rb2Se.

the product of charges is higher in BaTe and the sum of ionic radii are quite nearly the same, (135+97)pm and (152+50)pm respectively. they have a smaller effect compared to the product of charges.

anyway, you can calculate the relative lattice energy.

L.E. = k (product of charges)/(sum of ionic radii)

k is a constant, it's going to be the same for all the ionic compounds, ignore it.
just divide the product of charges by the sum of ionic radii.

http://en.wikipedia.org/wiki/Ionic_radius
 
  • #3
thank you
 

1. What is lattice energy?

Lattice energy is the amount of energy released when oppositely charged ions come together to form a solid compound. It is a measure of the strength of the ionic bonds in a compound.

2. How is lattice energy related to the stability of a compound?

The higher the lattice energy of a compound, the more stable it is. This is because a higher lattice energy indicates stronger ionic bonds, which are more difficult to break. Therefore, compounds with high lattice energy are less likely to decompose or dissociate.

3. What factors affect the lattice energy of a compound?

The lattice energy of a compound is affected by the charges of the ions involved and the distance between them. The smaller the ions and the higher their charges, the stronger the ionic bond and the higher the lattice energy. Additionally, lattice energy is also influenced by the type of ions and the crystal structure of the compound.

4. How do you arrange compounds by increasing lattice energy?

Compounds can be arranged by increasing lattice energy by considering the charges of the ions and their relative sizes. The general trend is that compounds with higher charges and smaller ion sizes have higher lattice energy. Additionally, compounds with the same ions but different crystal structures can also have different lattice energies.

5. Can the lattice energy of a compound be calculated?

Yes, the lattice energy of a compound can be calculated using the Born-Haber cycle, which takes into account the various factors that affect lattice energy. However, the calculation is complex and requires knowledge of the specific compound's properties. Lattice energy can also be estimated using the Born-Lande equation, which uses the charges and radii of the ions.

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