What is lattice energy and how does it differ among compounds?

tony
Written By tony

Tony is a writer and sustainability expert who focuses on renewable energy and climate change. He has been involved in the environmental movement for over 20 years and believes that education is the key to creating a more sustainable future. Tony is the founder of Gie.eu.com, a website dedicated to providing information on renewables and sustainability. He lives in California with his wife and two children.

 

 

 

 

Lattice energy is the energy required to break apart a crystal of a compound into its component ions. The higher the lattice energy, the more stable the compound is. There are several factors that determine lattice energy, including the size of the ions and the charge on the ions. In this article, we’ll explore how lattice energy differs among compounds and what factors influence it.

How to determine lattice energy

To determine whether BaS or CaO has the greater lattice energy, we need to consider the relative sizes of the ions because both compounds contain a +2 metal ion and a -2 chalcogenide ion. Because Ba 2+ lies below Ca 2+ in the periodic table, Ba 2+ is larger than Ca 2+. Similarly, S 2- is larger than O 2-. The larger the ion, the greater the lattice energy.

In general, anytime two ions of similar charge are compared, the one with the smaller radius will have the greater lattice energy. This is because the smaller ion can form stronger Coulombic bonds with the oppositely charged ion. The reason for this is that the smaller ion can get closer to the nucleus of the oppositely charged ion, and therefore the attractive force between the ions will be greater.

Ionic radius also trends across a period from left to right. As you go from left to right across a period, atomic radius increases because each successive element has an additional proton in its nucleus. This causes repulsion between the electrons in the outermost orbital, leading to a larger atomic radius. As a result, we would expect the lattice energy of BaS to be greater than that of CaO.

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An easy way to remember this is the saying “like Repels, unlike Attracts.” This means that when two ions have similar charges, they will repel each other, but when they have opposite charges, they will be attracted to each other. Therefore, two similar ions will have a lower lattice energy than two opposite ions.

According to the Law of reciprocal actions, the magnitude of the lattice energy is directly proportional to the product of the charges on the ions and inversely proportional to the distance between them. Given that both BaS and CaO contain a +2 metal ion and a -2 chalcogenide ion, we can use this law to compare the lattice energies of the two compounds.

If we consider the size of the ions, Ba2+ is larger than Ca2+, and S2- is larger than O2-. This means that the distance between the ions in BaS is greater than the distance between the ions in CaO. Therefore, given that the magnitude of the lattice energy is inversely proportional to the distance between the ions, we can conclude that BaS has a lower lattice energy than CaO.

What factors determine lattice energy?

The lattice energy of an ionic compound is determined by several factors, including the charge of the ions, the size of the ions, and the nature of the interatomic attractions:

  • The charge of the ions is one of the most important factors in determining lattice energy. Ions with a higher charge will have a higher lattice energy than those with a lower charge.
  • The size of the ions also affects lattice energy. Smaller ions will have a higher lattice energy than larger ones. This is because smaller ions can form stronger interatomic attractions.
  • Another factor that affects lattice energy is the nature of the interatomic attractions. Ionic compounds with strong interatomic attractions will have a higher lattice energy than those with weaker attractions.
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Which one of the following has highest lattice energy?

Mg2+ ion is smallest in size and thus has highest lattice energy.

Lattice energy is a measure of the strength of the attractive forces between atoms in a crystal. It is affected by the size of the atoms and the distance between them. Smaller atoms with stronger attractive forces will have higher lattice energies.

Mg2+ ions are the smallest of the four ions listed, and so they have the strongest attractive forces between them. This means that they have the highest lattice energy.

The other three ions, Ca2+, Sr2+, and Ba2+, are all larger than Mg2+. This means that there are weaker attractive forces between these ions, and so they have lower lattice energies.

In general, cations (positively-charged ions) have higher lattice energies than anions (negatively-charged ions). This is because the cations are smaller than the anions, and so they have stronger attractive forces.

What is the lattice energy of NaCl?

The lattice energy of NaCl is 787.3 kJ/mol, which is only slightly less than the energy given off when natural gas burns. The bond between ions of opposite charge is strongest when the ions are small.

The lattice energy of NaCl is the measure of the strength of the electrostatic force between the cations and anions in a crystal of NaCl. This force holds the crystal together and is responsible for the ionic character of NaCl.

The lattice energy is affected by several factors, including the size of the ions and their charge. The larger the ions, the greater the repulsive forces between them, and the weaker the overall attractive force. The lattice energy of NaCl is therefore lower than that of other ionic compounds with smaller ions, such as LiF.

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The charge on the ions also affects the lattice energy. The greater the charge, the greater the electrostatic attraction between the ions, and the higher the lattice energy. The lattice energy of NaCl is therefore higher than that of compounds with similar-sized ions but less charge, such as MgO.

How does lattice energy depend on ion size?

  • Lattice energy is the energy released when an ionic compound is formed from its component ions. The magnitude of the lattice energy depends on the size of the ions and the charge on them. In general, lattice energy increases as the charge on the ion increases and the size decreases.
  • Hydration energy is the energy released when a molecule or ion dissolves in water. The magnitude of the hydration energy also depends on the size of the molecule or ion and the charge on it. In general, hydration energy increases as the size of the molecule or ion decreases and charges on it increases.
  • The solubilities of carbonates, sulphates and phosphates of alkaline earth metals are much less than those of the corresponding alkali metals. This is because the lattice energies of these compounds are much higher than those of the corresponding compounds of alkali metals.