Lattice Energy

here. We're going to say that lattice formation energy is the change in energy. When separated gaseous ions combined to form an ionic solid. So here we're gonna have sodium ion in its gaseous state chloride ion in its gaseous state. They're opposite charges Causes them to combine together to give us an A C L solid realize here that were forming bonds. So it is an ex, a thermic reaction. That's why Delta h years negative. Now, in an extra thermic reaction, we release energy in order to create this new bond and realize here that theme or negative the lattice energy value than the mawr eggs a thermic the reaction becomes so just remember more dealing with lattice formation energy. We have gaseous ions as reactant, and they combine together to give us a mole of an ionic solid

So here it says the lattice formation of magnesium bromide is the energy change for which of the following processes. So remember, in a lattice formation reaction, we have the Ionic gasses combining to form an ionic solid. So here, magnesium is in group two way, so it's two plus boards charge. So this is good, bro means and groups seven a. So it's minus one. So this is good. And then remember they combined together to form an ionic solid, not a gas. So this is out, he answered. The only answer that can work is option three. None of the others work because they don't have ions to begin with that combined to form an ionic solids. So here are answer would be choice, see?

under lattice formation energy. We talked about ions forming an ionic solid, but in lattice association energy, we're doing the opposite here. It's the change in energy of one mole off solid crystal as its scattered into gaseous ions. So here we would have our sodium chloride solid. And what would happen is we would split it up into its ions here. So gashes, sodium ion and gashes. Chloride island This reaction is Indo thermic. Here we absorb energy in order to break the bond in order to split it up into its ions and because we're absorbing energy. That's why Delta H now is positive in terms of science. Now we're going to stay here. The more positive you're lattice energy value than the more Indo thermic the reaction will be.

here, it says Which of the following reactions is associated with the latticed association of lithium oxide. Now with lattice association, we start out with a solid ionic compound, so we're starting out with a lithium oxide solid. That means that these three air out and remember, it's an endo thermic process. So we absorb energy toe break this ionic solid into gaseous ions. So they have to have charges and they have to be in their gaseous state. That means Option four, which corresponds to choice d would be the right answer.

here. We're gonna take a look at the lattice energy formula. We're gonna say by simplifying columns, law. Ah, general formula for lattice energy could be used to determine Ionic bond strength. We're going to say here the higher the lattice energy than the stronger the Ionic bond. Now the formula is lattice. Energy equals Q one overtimes Q two over our This translates into the absolute value. So that means the answer is always gonna be positive. On top of the cat ion charge times the an ion charge and are here is radius. But when we simplify it, it means that we're adding the radius of the cat Ion and the radius of the anti on not realize here that the radius of the ion equals the period or row of the periodic table. So using this simplified lattice energy formula, we can compare different Ionic bonds

So here it's saying which compound possesses the strongest Ionic bond? We have magnesium bromide versus potassium chloride. So for magnesium bromide, we break it up into its ions. So that breaks up into magnesium two plus NPR minus one for their lattice energy. Remember, it's their charges in absolute terms. So plus two times negative one divided by their period numbers added together. So magnesium, if you look on the periodic table is in row three. Brahman is in row four. So that is to substance for its lattice energy. Potassium chloride made up of potassium ion and chloride ion look and see where they are on the periodic table. So remember, we multiply their charges in absolute terms. Now look on the periodic table. Potassium is in the fourth row of the periodic table, so period for chlorine is in the third row. So here lattice energy equals 1/7. So if you compare the two, we see that magnesium bromide has a larger lattice energy, and therefore it has a stronger ionic bond. Remember, the stronger your your lattice energy or high your lattice energy, and the stronger your Ionic bond will be

Now the lattice energy of an ionic solid has a direct impact on its physical properties. Here, we can say recall an increase in a lattice energy causes an increase in the strength of an ionic bond. And we can say here, as we increase the lattice energy are ionic bond gets stronger, so the ions air helped more tightly together. That would result in a higher boiling point. High melt, higher melting point. But then, ah, lower Saudi ability. Saudi ability is how easily things break up and separate. But if you have a lot of lattice energy, you're held mawr together tightly. Your Ionic bond is stronger. So just remember the direct relationship between lattice energy, ionic strength, boiling point and melting point. But the inverse relationship lattice energy has to Saudi ability.

here. It says, choose the compound below. That should have the highest melting point according to the Ionic bonding model. So remember, highest melting point means highest lattice energy. When you break these all up into their ions, based on the groups that they're found in, we'll be able to figure out the charge here. Remember group number and their charges. Come now, we're gonna say lattice energy for all of them. In absolute brackets, we have their charges multiply together on the bottom. We're going to have the periods that they're founded. So here all I'm doing is I'm in putting the charges for each one. So remember, that's the first part we need for lattice energy. So here we're gonna multiply their charges in absolute terms. So for all of them, the number will be positive. Now, take the periods or rose that they found on the periodic table, and they're gonna go on the bottom, but they're added together. So this would be three plus two. This would be three plus 23 plus two and three plus three. Now we're going to bring everything down. So this is 9/5. This is 1/5 this is 4/5, and finally, this one here is 1/6. The one with largest lattice energy is aluminum nitride, and because of that, it will have the highest melting point. So just remember the higher lattice energy, the higher your melting point, the higher your boiling point. And remember, the lower your solid ability. I know the question doesn't talk about boiling point in Saudi ability, but it's important to remember these relationships.