Some of the important properties of ionic compounds are as...

Name: Problem 20, Chapter 3: Chemistry An Atoms First Approach
Uploaded: 2020-07-03T20:27:41-08:00
Duration: 6 min 19 s
Channel: Bryan Li
Description: Some of the important properties of ionic compounds are as follows: i. Iow electrical conductivity as solids and high conductivity in solution or when molten ii. relatively high melting and boiling points iii. brittleness iv. solubility in polar solvents How does the concept of ionic bonding discussed in this chapter account for these properties?

Some of the important properties of ionic compounds are as follows: i. Iow electrical conductivity as solids and high conductivity in solution or when molten ii. relatively high melting and boiling points iii. brittleness iv. solubility in polar solvents How does the concept of ionic bonding discussed in this chapter account for these properties?

Some of the important properties of ionic compounds are as follows:
i. Iow electrical conductivity as solids and high conductivity in solution or when molten
ii. relatively high melting and boiling points
iii. brittleness
iv. solubility in polar solvents
How does the concept of ionic bonding discussed in this chapter account for these properties?

Key Concepts

Brittleness in Ionic Solids

Ionic solids are typically brittle because when a force is applied, it can shift the layers of ions within the lattice. This displacement may force ions of like charge into proximity, resulting in strong repulsive forces that cause the crystal to fracture rather than deform, leading to brittleness.

Ionic Bonding and Lattice Structure

Ionic bonding involves the electrostatic attraction between positively and negatively charged ions. In ionic compounds, these interactions result in a well-arranged, repeating three-dimensional lattice structure, where ions are held in fixed positions. This regular arrangement is fundamental to the distinctive physical properties observed in ionic compounds.

Electrical Conductivity of Ionic Compounds

In the solid state, ionic compounds have low electrical conductivity because their ions are locked in place within the lattice, preventing them from moving freely. When an ionic compound is molten or dissolved in a solvent, the lattice structure is disrupted, allowing the ions to move and thereby conduct electricity.

Lattice Energy and High Melting/Boiling Points

The high melting and boiling points of ionic compounds can be attributed to the significant lattice energy, which is the energy required to overcome the strong electrostatic forces between the oppositely charged ions. This high energy barrier makes ionic compounds stable at elevated temperatures until sufficient heat is applied to break the lattice apart.

Solubility in Polar Solvents

Ionic compounds are generally soluble in polar solvents due to ion-dipole interactions. The polar molecules of the solvent are attracted to the ions in the ionic lattice, helping to pull them away and surround them in solution. This solvation process overcomes the ionic bonds by lowering the energy of the system.

Transcript

00:01 All right, in this question, we're going to talk about a few properties of ionic compounds.

00:05 So, first up, we have conductivity.

00:09 Ionic compounds, they're very conductive, but they're dissolved in water, but not so much when they're in solid form.

00:15 Now, let's talk about why.

00:17 When they're dissolved in water, remember, ionic compounds have a cation and an ion, and when they're dissolved in water, these cations and aniones are separated.

00:30 So we have positive and negative charges floating around.

00:37 That allows electrons to find a route through a solution of cations and anions.

00:45 When they're tightly bound in a crystal structure, they don't have that luxury because there are too many repulsion forces.

00:57 So if we think about what, let's use sodium chloride looks like, we have.

01:03 Sodium, we've got chlorine, we've got alternating sodium and chlorine atoms in a huge clump.

01:19 So as soon as the electron, it may be attracted to a sodium, as soon as the electron gets to one part, it's going to be met with repulsion forces from all the chlorines around it.

01:32 It would be very difficult for it to move through.

01:35 And in a solution, that's not a problem because the cat ions and anions are spread apart.

01:46 So electrons can come in and avoid, well, or squeeze by these negatively charged anions.

01:56 Right? next up we're talking about melting points.

01:59 So that's kind of a similar story where we have, if we look at the structure, it forms a okay, i'll draw it this way, actually.

02:11 Sorry.

02:14 So i have a compound, say, form a crystal lattice structure.

02:26 Pick one where, well, let's do, chlorine is red and sodium is black...

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