Lattice energy of nacl series#

Lattice energy of nacl series#

It represents a series of steps leading to the formation of an ionic compound from its constituent gaseous ions.The Born-Haber cycle deals with ionic compounds only where metals tend to form cations, and non-metals form anions. To calculate the enthalpies we need to follow The Born-Haber cycle. The standard atomisation enthalpy is the enthalpy change when 1 mole of gaseous atoms is formed from the element in its standard state.Įnthalpy change of atomisation is always positive. We also need to define the atomisation enthalpy, ΔH°a: The enthalpy change accompanying a chemical change is independent of the route by which the chemical change occurs. To calculate the enthalpy energy is necessary to be familiar with Hess's Law: Trends of the main forces and atoms properties in the periodic table. Notice that the lattice energy increase in the period and decrease in the group on the periodic table.įigure2. Lattice energy therefore decreases down a group on the periodic table.īelow there is a very useful picture of the periodic table and the trends of all the main important forces and atoms characteristics. Using the sample above, the enthalpy of MgO is also much bigger than NaCl one because Mg atom is smaller than Na and O atom is smaller than Cl. Therefore, as ionic size increases, lattice energy decreases. The smaller are the radius of the ions, the closer the charges are, the bigger is the attraction between them and consequently the greater is the lattice enthalpy. As Mg has 2 positive charges +2, they attract the negative charges O -2 more than the charge of Na + 1 attracting only one negative Cl – 1.

For example, Sodium chloride NaCl and magnesium oxide MgO have exactly the same arrangements of ions, but the lattice enthalpies are very different. The greater is the charges of the ions, the greater is the attractions between them, and consequently the greater is the lattice enthalpy. The main factors affecting the lattice enthalpy are the ions charge and the ions radii.

This force ceases to exists only when the salt is at the gaseous state, therefore when the ions are scattered too far away to each other. This energy is released when bonds are made and is needed to break bonds. The greater the lattice enthalpy, the stronger the forces, and higher is the energy released in the environment when the crystal is formed. Lattice enthalpy is a measure of the strength of the forces between the ions in an ionic solid. The formation of a solid crystal usually releases a huge amount of energy into the environment hence, the process is exothermic, and therefore its value is always negative. If we take NaCl as example and we want to prepare sodium chloride crystal lattice, the lattice enthalpy of sodium chloride will be the energy necessary to form solid sodium chloride crystal from gaseous sodium and chloride ions. Lattice energy is the energy required to separate 1 mol of an ionic solid into gaseous ions. Lattice enthalpy and lattice energy are commonly used as if they mean exactly the same thing, although there is a difference between them which relates to the conditions under which they are calculated. Lattice enthalpy (H) values are usually represented in kilojoules (KJ). Lattice enthalpy is usually applicable to ionic compounds, which are compounds formed by metals and non-metals. For example, if we say 'sodium chloride crystal lattice', we mean a regular geometrical pattern of sodium and chloride ions. The 3-dimensional arrangement of atoms or ions in a organised crystallin pattern within is referred as crystal lattice. In chemistry, when the term lattice is used, we usually refer to a crystal lattice which is a highly transparent substance with a regular geometric shape.

The Born-Haber cycle represents a series of steps leading to the formation of an ionic compound from its constituent gaseous ions.

Lattice enthalpy increases with the charges and decreases with the size of the ions.

Lattice energy is the energy required to separate 1 mol of an ionic solid into gaseous ions.

Lattice enthalpy is a measure of the strength of the forces between the ions in an ionic solid.

Key Facts & Summary of Lattice Enthalpy:.