State of Most Ionic Compounds

Most ionic compounds form ionic solids or crystals. The crystal lattice is made up of repeating units called formula units. I’m going to call these formula units, but know we could also call these repeating units, because that’s essentially what’s happening there.

They’re repeating. Now take, for example, table salt. The ionic bonds of attraction between the chloride ion and the sodium ions around it hold the crystal together. I’m going to put here “ionic bonds of attraction”. That’s what is holding everything together.

Now, the crystal of sodium chloride is cubic. I’m going to put that over here. For every sodium ion, you have 6 chloride ions surrounding it. Around each chloride ion, you have 6 sodium ions surrounding it. If you think about this right here, that has to go right there.

There has to be sodium ions all around this, but there are also has to be chloride ions around every sodium ion. It’s very symmetrical. 6 chloride ions around every sodium ion and 6 sodium ions around every chloride ion. Generally, ionic compounds stay bound to crystals unless dissolved in water.

I’m going to write here “they stay bound unless dissolved in water”. At that point, you all know if you put salt in water the salt is going to dissolve. You’re not going to see the salt in there anymore. Once dissolved, the ions are going to float freely in the solution surrounded by water molecules.

Ionic crystals come in many shapes and colors. Think about any type of gem that’s very colorful. That is going to be (probably) an ionic crystal. Hopefully through this you have a better idea of the state of most ionic compounds. It’s important to remember that most ionic compounds form ionic solids or crystals.