Skip to main content
Pearson+ LogoPearson+ Logo
Start typing, then use the up and down arrows to select an option from the list.

General Chemistry

Learn the toughest concepts covered in Chemistry with step-by-step video tutorials and practice problems by world-class tutors

2. Atoms & Elements

Ions

Ions represent elements that possess either a positive charge or a negative charge. 

Determining Ionic Charge
1
concept

Ions Concept 1

clock
1m
Play a video:
Was this helpful?
At this point, we have just examined Adams, where we're dealing with the neutral element that has the same number of protons and electrons. Now, when the number of protons and electrons are different, that's what we go into ions. Ions themselves are created from loss or gaining of electrons by elements. So in the creation of an ion, or either losing electrons or gaining electrons, we're going to stay here. When an element loses electrons, it becomes a positively charged ion called a cat ion. Now this makes sense. You're losing negatively charged electrons. If I'm losing something negative, I'm becoming more positive now. On the other end, when an element gains electrons so it's gaining negative electrons, it becomes a negatively charged ion called in an ion. So just remember, cat ions are positively charged. Ions and ions are negatively charged ions. We're going to stay here a new term. Isil electronic. This is what elements have the same number off electrons. So just remember the difference between atoms and ions is that atoms have the same number of protons and electrons. But when we become an ion, we've either lost electrons or gained electrons. This causes a difference in the number of protons and electrons within a given element, so keep that in mind when dealing with ions.

Ions are formed from either the loss or gaining of electrons by a neutral element.

2
concept

Ions Concept 2

clock
6m
Play a video:
Was this helpful?
Now let's see exactly how these positive ions and negative ions come about. If we take a look at the first one, we have a representation of an atom. Here. Here we have 11 or five and then beat. Remember, 11 represents our mass number, which is just the number of protons and neutrons together on the bottom. We have our atomic number, which represents the number of just protons. How do we know our atomic number is five. If we look at the model of the atom here we have one, 2345 for the number of protons. If we were to look on the periodic table, we'd see that the only element on the periodic table with an atomic number five would have to be boron. That's why the letter here is beat. Now, what we need to realize next is how maney electrons do we have within this Adam. Well, we have five electrons because we have 1234 and electrons. So we have Here are five protons and we have here five electrons. Okay, They're equal to one another. And if you were to think about it, five protons each one. Having a charge of plus one would mean that this is plus five five electrons, each with a negative. One charge would mean that this is negative. Five, if you add plus five and negative five together, they totally cancel one another out. So you have a number of zero. That means that this representation of boron is neutral. So this is the boron Adam. If we go to the other image of boron notice that we have here this first circle, right, this first circle here has two electrons in it. And then we have this second circle here which has three electrons in it. But in the other picture of boron, the second circle is now gone. Those three electrons are no longer there. All we're left with is two remaining electrons. So if we look, the number of protons within the nucleus hasn't changed. It's still 12345 So we still have five protons. But now we only have 12 electrons. If we think about it, this would be plus five plus minus two, right, Because of the two electrons. When you add those together, you have plus three as your answer so we have a charge of plus three or you could write it as three plus. So talk to your professor. Some professors don't care if it's written as plus three or three plus. Traditionally, we write the number before the charge, but it really doesn't matter now here because it has a charge of plus three or three. Plus, it represents an ion remembering ion will have a charge because it's either lost or gained electrons. In this case, it's lost three electrons who becomes plus three. So this represents our boron ion. If we take a look at what the next part with the and ions we have here oxygen, oxygen, elemental symbol is Oh, we see here that it has an atomic number of eight. So it has eight protons, and then here it's mass number. It's six. That means it has it's gonna have represent protons and neutrons together. So we know that this boron this oxygen has eight protons. Let's count the number of electrons. So we have It has eight electrons, so these numbers are equal to one another. So if we did plus eight plus negative eight. That would give us zero at the end. So this is our oxygen atom. Now. What's the difference between this representation of oxygen and the other one? Well, you should notice that the outer circle had originally six electrons on it, but now we've gained two additional electrons. So now there's eight electrons on the outside now. The number of protons, of course, is not changing. Because remember to create an eye on your either gaining or losing electrons. The other subatomic particles, protons and neutrons stay what they are. So here we have eight protons. And then if you count up all the electrons and add those two additional ones So 10 We have 10 electrons, so that would be plus eight plus minus 10 equals negative too. So the charge here would be minus two or two minus. Again, you can either put the charge before the number or the number before the charge. It really is a case by case basis with professors because some professors really don't care if you right tu minus for the ion or minus two. So make sure you talk to them and make sure which version they want. So here it has a chart, So this would be the oxygen ion. So just remember, this is what's really going on. When we're losing electrons, we gain a positive charge. When we're accepting or gaining electrons, we gain a negative charge. Now that we know the idea behind ion formation, let's continue on to some questions and let's see if we can determine what the charges are. How many subatomic particles are present for any given ion?

A positively charged ion is called a cation and a negatively charged ion is called an anion

3
example

Ions Example 1

clock
2m
Play a video:
Was this helpful?
So here in this example question, it states determine the number of protons, neutrons and electrons for the following cat ion. Now it's a cat ion because it possesses a positive charge, that positive charge being three plus now, when looking at the other numbers, we know that this 13 here represents our atomic number, which uses the variables. E remember the atomic number gives us the number of protons, and because it's 13, that means we have 13 protons. That means that option. He cannot be an answer, because here we do not have 27 protons. Next, we have the number above the 13 and 27. Remember, that is your mass number, which uses the variable A. Your mass number gives you the number of protons plus neutrons within the element or ion. From this information, we know that the number off neutrons would equal a minus Z, so it's the mass number minus the atomic number, So that would be 27 minus 13, which would give us 14 neutrons. So so far, options B and C can be the only correct choices because in a we do not have 27 new trials. Now the charge is three plus three plus means that you have lost electrons. It means you have lost three electrons. When aluminum is neutral has no charge. It has an equal number of protons and electrons. Okay, but now we've lost three electrons. So what does that mean? That means we have 10 electrons remaining. So the answer would have to be see here. And if you want to double check that, you could just say we have 13 protons and 10 electrons, so we know that would be plus 13 plus minus 10, which would give us plus three as an answer. That proves that our charge should be plus three here. So, out of all the choices present Onley option C gives the correct number for each of the subatomic particles.
4
Problem

Give the correct number of protons, neutrons and electrons for the following isotope:.

5
Problem

In which pair are the two species both isoelectronic and isotopic?

6
Problem

One isotope of a metallic element has a mass number of 65 and 35 neutrons in the nucleus. The cation that this atom forms has 28 electrons. What is the symbol of the cation?

7
Problem

Which of the following is the symbol for the ion with a +4 charge, 30 neutrons and 21 electrons?

8
Problem

Fill in the gaps for the following table.

Was this helpful?
Divider