What is an ionic compound ??

Question

Please help me out and also put the formula if you know please..thank you

Answer 1

Ionic compounds are basically defined as being compounds where two or more ions are held next to each other by electrical attraction. One of the ions has a positive charge (called a "cation") and the other has a negative charge ("anion"). Cations are usually metal atoms and anions are either nonmetals or polyatomic ions (ions with more than one atom). Think back to grade school: The same thing that makes the positive and negative ends of a magnet stick to each other is what makes cations and anions stick to each other.

Usually, when we have ionic compounds, they form large crystals that you can see with the naked eye. Table salt is one example of this - if you look at a crystal of salt, chances are you'll be able to see that it looks like a little cube. This is because salt likes to stack in little cube-shaped blocks.

Sometimes when you see a salt, it looks like a powder instead of a cube. This doesn't mean that the salt is not a crystal - it means that the crystals are just so small that you can't see them with the naked eye. If you were to put the powder under a microscope, chances are that you would see little geometric blocks.

So, how do we name cations? If the cation is a main block element, the name of the cation will just be the name of the element. So, the Na+ ion is the "sodium" ion. Not too challenging. However, if the cation is a transition metal, what you need to do is to check out whether or not there is more than one possible charge for that element. For example, iron can have a charge of either +2 or +3. As a result, you need to specify whether the cation has a +2 or a +3 charge. When you've done this, just put the number after the name of the element in Roman numerals. For example, the Fe+3 ion just has the name "iron (III)".

How about anions? If the anion has only one atom in it, then the name of the anion is the same as the name of the element EXCEPT the end of the element name is taken off and "-ide" is added to the end. Thus, oxygen becomes "oxide", sulfur becomes "sulfide", phosphorus is "phosphide", et cetera. If the anion has more than one atom, then we'd say that it's a "polyatomic ion", meaning (not surprisingly) that the anion has more than one atom. Look up the polyatomic ion in a table (or pull it out of your... uh... memory), and you've got the name. Thus, OH- is "hydroxide", SO42- is sulfate, et cetera.

Naming ionic compounds if you're given the formula

Let's go through this using an example: Fe2(SO4)3

Step One: Name the cation and anion
The cation is always the first thing you see in the name, and the anion is always the second thing. In this case, you should recognize that Fe is "iron", and that SO4 is the "sulfate" ion. Generally, if one of these ions has more than one atom in it, you'll need to look it up in a chart. If you're one of my students, you need to have eight of the polyatomic ions memorized: hydroxide, nitrate, nitrite, sulfate, sulfite, carbonate, phosphate, ammonium. If you don't know the formulas, look 'em up.

Step Two: Figure out if you need a Roman numeral in the name.
If the cation in the compound you're naming is not a transition metal, then you definitely don't need to use a Roman numeral and the naming is done. If there is, then you need to figure out whether or not the cation can exist in more than one charge. If not, then you don't need a Roman numeral. If so, then move on to Step Three...

Step Three: Figure out what the Roman numeral should be
Basically, this should be fairly easy. A good rule of thumb is that usually the number of anions you have in the molecule is equal to the charge on the cation, and that the number of cations you have is equal to the number of anions. Using our example, there are three sulfate ions, meaning that iron has a charge of +3. Likewise, since there are two iron atoms, the sulfate has a charge of -2. Since iron has a charge of +3 in this compound, the name in this example is iron (III) sulfate.

Step Four: Check your work
Look at the answer from the last step, and ask yourself whether the charges are OK. Is +3 a charge that iron can have? Is -2 the charge of the sulfate ion? In this case, the answer to both questions is "yes", so we're finished, and the answer of iron (III) sulfate stands.

Naming ionic compounds if you're given the formula

Let's go through this using an example: Fe2(SO4)3

Step One: Name the cation and anion
The cation is always the first thing you see in the name, and the anion is always the second thing. In this case, you should recognize that Fe is "iron", and that SO4 is the "sulfate" ion. Generally, if one of these ions has more than one atom in it, you'll need to look it up in a chart. If you're one of my students, you need to have eight of the polyatomic ions memorized: hydroxide, nitrate, nitrite, sulfate, sulfite, carbonate, phosphate, ammonium. If you don't know the formulas, look 'em up.

Step Two: Figure out if you need a Roman numeral in the name.
If the cation in the compound you're naming is not a transition metal, then you definitely don't need to use a Roman numeral and the naming is done. If there is, then you need to figure out whether or not the cation can exist in more than one charge. If not, then you don't need a Roman numeral. If so, then move on to Step Three...

Step Three: Figure out what the Roman numeral should be
Basically, this should be fairly easy. A good rule of thumb is that usually the number of anions you have in the molecule is equal to the charge on the cation, and that the number of cations you have is equal to the number of anions. Using our example, there are three sulfate ions, meaning that iron has a charge of +3. Likewise, since there are two iron atoms, the sulfate has a charge of -2. Since iron has a charge of +3 in this compound, the name in this example is iron (III) sulfate.

Step Four: Check your work
Look at the answer from the last step, and ask yourself whether the charges are OK. Is +3 a charge that iron can have? Is -2 the charge of the sulfate ion? In this case, the answer to both questions is "yes", so we're finished, and the answer of iron (III) sulfate stands.

Other stuff I might have forgotten above

In no particular order, here's some other stuff about ionic compounds that you might have wondered about:

* Ionic compounds are usually formed when metal cations bond with nonmetal anions. The only common exception I know to this is when ammonium is the cation - there's no metal in ammonium, but it forms ionic compounds anyhow.
* Ions are atoms that have satisfied the octet rule (which for those of you who've been sleeping the last couple of months, states that every atom wants to have eight valence electrons, just like the nearest noble gas). If you have two neutral elements, and one wants to gain electrons to be like the nearest noble gas and the other wants to lose electrons to be like the nearest noble gas, chances are that they will react with each other and make an ionic compound.

Answer 2

In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. The positively charged ion is usually a metal ion and the negatively charged ion is non-metallic element or molecule.

Picture in the link

Answer 3

Ions are generally considered to be atoms with an electron knocked out of orbit, although it can also mean one with an extra electron pulled into orbit about the atom. As far as a formula, I'm a theoritician, not an experimentalist....mainly because I didn't want to deal with all that math.

Answer 4

salt

NaCl