Since all ionic compounds are developed when anions and also cations are attracted to one another, ionic compounds frequently have comparable characteristics.

You are watching: Most ionic substances are brittle. why

Ionic Compounds Form Crystals

Ionic compounds consist of cations and also anions that stick alongside each various other bereason of their opposite charges. Imagine a single lithium cation stuck beside a single chlorine anion to develop lithium chloride. Now, it"s unmost likely that just one lithium ion and also one chloride ion will certainly be present in this location?generally, as soon as we sheight of chemical reactions, we"re talking about a vast number of atoms undergoing a reaction in a very tiny place (one teaspoon of salt consists of approximately 1022 atoms). As an outcome, if our single LiCl pair were to come close to one more LiCl pair, the adhering to would take place:

Because oppositely charged ions entice one one more, the LiCl pairs will certainly tend to create larger teams. These bigger groups, in turn, will create even bigger groups of ions, as presented in the adhering to figure:


Figure 8.3The positive charge on the lithium cation of one pair will certainly be attracted to the negative charge on the chloride ion of the other pair.

Figure 8.4This procedure, where stacks of LiCl ions incorporate with one another, will certainly continue until tright here are no even more lithium or chloride ions.

Molecular Meanings

Crystals are huge arrangements of ions or atoms that are stacked in continuous trends. Many type of ionic compounds develop very large crystals.

These huge arrangements of ions are referred to as crystals. Though crystals are frequently developed from ionic compounds, they likewise exist in some other chemical compounds, such as diamonds. We"ll talk about this in a lot greater detail in Solids.


Hydprices are created once one or even more molecules of water connect themselves to ionic compounds. These compounds are interesting bereason they show up dry but offer off water as soon as heated. Particularly exciting is Epsom salt, or magnesium sulfate heptahydprice (MgSO47H2O). When heated, sufficient water is offered off that it actually dissolves the magnesium sulfate!

Ionic Compounds Often Have High Melting and also Boiling Points

What happens as soon as you warm somepoint up in your kitchen? You might have found while cooking (or while microwaving random things while bored) that many of the foodstuffs we eat either melt or burn once heated. Some foodstuffs even perform both! As you can more than likely guess, I"m an expert when it comes to placing out home fires.

Ionic compounds, on the various other hand also, frequently melt and also boil at a lot higher temperatures than various other materials. In order for ionic compounds to melt, enough energy must be included to make the cations and also anions relocate ameans from one another. Due to the fact that these attractions are so solid, it takes the majority of power to pull these ions acomponent. Adding this a lot power to ionic compounds calls for a great deal of warmth, which is why ionic compounds have exceptionally high melting and boiling points.

Ionic Compounds Are Hard and also Brittle

Imagine bashing a huge chunk of lithium chloride versus your head. What do you mean that can feel like? If you guessed that it would hurt choose crazy, you were appropriate. Like many type of ionic compounds, lithium chloride is as tough as a rock.

Ionic compounds are extremely hard bereason it is hard to make the ions relocate acomponent from each other in a crystal. Even if you apply an excellent deal of force on the crystal (imagine running headlengthy into a gigantic wevery one of lithium chloride), the attraction between the cations and anions will frequently proceed to host the crystal together.

Let"s say, though, that you really want to break acomponent an ionic compound. While extremely tough, ionic compounds are additionally generally incredibly brittle, definition that they break acomponent as soon as the ideal kind of force is applied. As the adhering to number reflects, where you use the pressure is simply as important as how much pressure you use.

Figure 8.5By using pressure in a means that pries the cations and also anions apart from each other: you have the right to cause a crystal to completely break apart.

As you have the right to see from this diagram, ionic crystals align themselves such that there are regions wright here a tiny force deserve to break apart the crystal. These regions are periodically referred to as "cleavage planes" because they are the areas wright here the crystal is weakest and deserve to the majority of easily be damaged.

Ionic Compounds Conduct Electricity When Disaddressed in Water or Melted

Once upon a time, tbelow was an inventor who came up with a device for drying hair. This "hairdryer" as he dubbed it, heated air via power and also blew it throughout the hair of the perchild holding it. Since water evaporates as soon as heated, the hair dried even more quickly. This inventor"s legacy lives on to today in a family members appliance loved by millions.

Molecular Meanings

Electrolytes are compounds that conduct electricity when dissolved in water. Many ionic compounds are considered to be electrolytes. However, some ionic compounds don"t disresolve in water. As a result, they do not share this residential property.

Shortly afterward, tbelow was a male that decided that he didn"t want to wait to acquire out of the bathtub prior to drying his hair. His legacy: A hairdryer warning sticker via a photo of a man acquiring electrocuted.

When ionic compounds are put in water, they reason the water to conduct electricity. Generally, water doesn"t conduct electrical energy well at all. However before, as soon as salts disdeal with in water, they break up right into their constituent cations and anions and it is the visibility of these ions that allows it to conduct power. Because salts conduct electricity when dissolved in water, they are described as electrolytes.

In the exact same means, pure salts also conduct electrical energy when they are melted. As a solid, the anions and cations in an ionic compound are locked in place and also unable to move electric charge. However, when the ionic compound is melted, these ions are totally free to relocate approximately and conduct charge.

Excerpted from The Complete Idiot"s Guide to Chemisattempt 2003 by Ian Guch. All civil liberties scheduled including the right of reproduction in totality or in part in any develop. Used by setup with Alpha Books, a member of Penguin Group (USA) Inc.

See more: Abogado De Divorcios En Maryland Cuanto Cuesta Un Divorcio En Estados Unidos Usa

To order this book direct from the publisher, visit the Penguin USA website or contact 1-800-253-6476. You can additionally purchase this book at and Barnes & Noble.