Ions - Online Tutor, Practice Problems & Exam Prep

Ions are atoms that have gained or lost electrons, resulting in a net electrical charge. When an atom loses electrons, it becomes a cation, which is a positively charged ion. Conversely, when an atom gains electrons, it becomes an anion, a negatively charged ion. The atomic number, indicating the number of protons, remains unchanged during ion formation. For example, a neutral boron atom with five protons and five electrons becomes a boron cation with a +3 charge after losing three electrons. Similarly, an oxygen atom with eight protons and eight electrons becomes an oxygen anion with a -2 charge upon gaining two electrons. Understanding ion formation is crucial as it underpins many chemical reactions, including the formation of compounds and the principles of electrochemistry.

Ions Concept 1

At this point we've just examined atoms where we're dealing with a 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 the 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 say here when an element loses electrons, it becomes a positively charged ion, called a cation. 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 an anion. So just remember, cations are positively charged ions and anions are negatively charged ions.

We're going to say here a new term, isoelectronic. This is when elements have the same number of 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 Concept 2

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 115 and then B. 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 justice protons. How do we know our atomic number is 5? If we look at the model of the atom here, we have 12345 for the number of protons. If we're to look on the periodic table, we'd see that the only element on the periodic table with an atomic number 5 would have to be boron. That's why the letter here is B.

Now what we need to realize next is how many electrons do we have within this atom? Well, we have 5 electrons because we have 1234 and 55 electrons. So we have here are 5 protons, and we have here 5 electrons. OK, they're equal to one another. And if you were to think about it, 5 protons, each one having a charge of plus one, would mean that this is +5. 5 electrons each with a -1 charge would mean that this is -5. If you add +5 and -5 together, they totally cancel one another out, so you'd have a number of zero. That means that this representation of boron is neutral. So this is the boron atom.

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 2nd circle is now gone. Those 3 electrons are no longer there. All we're left with is 2 remaining electrons. So if we look, the number of protons within the nucleus hasn't changed. It's still 12345. So we still have 5 protons, but now we only have 1-2 electrons. If we think about it, this would be +5 plus -2, right? Because of the two electrons. When you add those together, you'd have +3 as your answer. So we have a charge of +3. Or you can 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. Remember, an ion will have a charge because it's either lost or gained electrons. In this case it's lost three electrons so it becomes +3. So this represents our boron ion.

If we take a look at the next part with the anions we have here oxygen, oxygen elemental symbol is O. We see here that it has an atomic number of eight, so it has 8 protons and then here its mass number is 6. So that means it has it's going to have represent protons and neutrons together. So we know that this boron this oxygen has 8 protons. Let's count the number of electrons. So we have 123456 7-8. It has 8 electrons, so these numbers are equal to one another. So if we did +8 plus -8 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 6 electrons on it, but now we've gained two additional electrons, so now there's 8 electrons on the outside. Now, the number of protons of course is not changing, because remember to create an ion you're either gaining or losing electrons. The other subatomic particles, protons and neutrons stay what they are. So here we have 8 protons and then if you count up all the electrons and add those two additional ones SO1234 567-8910, we have 10 electrons. So that would be plus 8. Plus -10 equals -2 so the charge here would be -2 or 2 minus.

Again, you can either put the chart 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 write 2 minus for the ion or -2. So make sure you you talk to them and make sure which version they want. So here it has a charge. So this would be the oxygen ion O. 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?

Ions Example 1

So here in this example question it states determine the number of protons, neutrons and electrons for the following cation. Now it's a cation because it possesses a positive charge, that positive charge being 3 plus. Now when looking at the other numbers we know that this 13 here represents our atomic number which uses the variable Z. 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 D cannot be an answer because here we do not have 27 protons.

Next we have the number above the 13 in 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 of neutrons would equal A-Z. So it's the mass number minus the atomic number. So that would be 27-13=14 neutrons. So so far options B & C can be the only correct choices because in A we do not have 27 neutrons.

Now the charge is 3+. 3 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. OK, 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 C here. And if you want to double check that, you can just say we have 13 protons and 10 electrons. So we know that would be +13+-10=+3, which would give us +3 as an answer. That proves that our charge should be plus three here.

So out of all the choices present, only option C gives the correct number for each of the subatomic particles.

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

• A. 35 protons, 35 neutrons, 81 electrons
• B. 35 protons, 46 neutrons, 36 electrons
• C. 81 protons, 46 neutrons, 82 electrons
• D. 35 protons, 46 neutrons, 34 electrons

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

• A.
• B.
• C.
• D.

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?

• A. ⁶⁵Zn
• B. ⁶⁵Ga³⁺
• C. ⁶⁵Zn²⁺
• D. ⁶⁵Ni²⁺

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

• A. ⁵⁵Mn⁴⁺
• B. ⁵¹Cl⁴⁺
• C. ⁵¹Mn⁴⁺
• D. ⁵⁸Ni⁴⁺

Fill in the gaps for the following table.

So here the practice question says, fill in the gaps for the following table. For the first column, we have our symbol, which encompasses our element symbol and its charge. This charge results from adding up all your protons and electrons, and for that reason, we can call it more specifically the net charge. So here, the net charge is 3 plus. Now for protons. We know that protons are equal to our atomic number Z. But here we don't have a column for atomic number Z, so we're going to say instead that the protons are connected to the electrons, and together they give us our net charge. Neutrons, we're going to say neutrons here, equal your mass number, which is A, minus Z, which is your atomic number. But, again, because we don't have atomic number as a column, we'll just say since Z equals the number of protons, we're going to say it's minus protons. Then electrons, you can also group with protons in order to determine our charge. The mass number here, mass number is A. It comes from looking at the number of protons plus neutrons within an element or an ion. The charge can again be determined by looking at the number of protons and knowing what its atomic number will be. We just look it up on the periodic table. So, CO is cobalt. It has 27 protons because its atomic number is 27. Next, determining the number of neutrons, we're going to take the mass number, which is 59, and subtract it by the 27 protons, and that'll give us 32 neutrons. For electrons, we can say here that the number of protons is 27. We don’t know how many electrons we have here, so electrons will be unknown. Then we're going to say next that our charge is plus 3 because here it's 3 plus. We're going to subtract 27 protons from each side. Now, this gives us negative 24, which makes sense because each electron is negatively charged, so that'll give us 24 electrons. So again, we get negative 24, but negative 24 means there are 24 negatively charged electrons. So you have to just consider it as 24. For the next one, we know the proton number is 34, so we know the atomic number. Looking on the periodic table, that would give us selenium or Se as our element symbol. The mass number comes from adding up the protons plus the neutrons, so that would give us 80 as our mass number. Then we know the number of protons we have is 34, plus our 36 electrons, that's negative 36 because each electron is negatively charged. So overall, this would be 2 minus or minus 2. So this would be a selenium ion, Se 2 minus. Next, we have 76 here. Look on the periodic table that gives us OS, which is osmium. The number of electrons would be 76, plus the number of electrons, which you don't know, plus the net charge, which is 2 plus or plus 2. Subtract 76 from each side. So that would give us negative 74, which really means we have 74 negatively charged electrons. The mass number here would be 76 protons, plus 116 neutrons, so that would give us 192. And then finally, we have here 80 as the number of protons. Look on the periodic table. Oh, actually one more thing, this would be osmium 2+. So we have 84 atomic number for the last column or last row, and that gives us HG, which is called mercury. The mass number would be the number of protons, which is 80, plus number of neutrons, which is 120. So that's 200 for our mass number. And then finally, to determine the overall charge at the end, we have 80 positive protons plus negative 78 for the 78 electrons. So that gives us overall a 2 plus charge. So this would be mercury 2+ ion. This is the approach you need to take in order to find out each one of the subatomic particles, net charge, and mass number for each of the given ions.

Here’s what students ask on this topic:

What are ions?

Ions are atoms or molecules that carry an electric charge. This charge results from the loss or gain of electrons, which are negatively charged subatomic particles. When an atom loses one or more electrons, it becomes a positively charged ion, known as a cation. Conversely, when an atom gains electrons, it becomes a negatively charged ion, known as an anion.

The process of becoming an ion is called ionization. Ions are essential in various chemical processes and play a crucial role in the function of living organisms. For example, they are key to the conduction of electrical signals in nerve cells and the transport of substances across cell membranes. In the environment, ions contribute to the electrical conductivity of water and the formation of minerals. They are also integral to many technological applications, such as batteries and electrolysis.

How are ions formed?

Ions are formed when atoms gain or lose electrons, resulting in a net electrical charge. Atoms are made up of protons, neutrons, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons have no charge. Normally, an atom is neutral because the number of protons and electrons is equal, balancing the charges.

However, if an atom loses one or more electrons, it becomes a positively charged ion, known as a cation. This can happen if an atom has a low electron affinity or if it comes into contact with an atom that has a much higher affinity for electrons.

Conversely, if an atom gains extra electrons, it becomes a negatively charged ion, called an anion. This typically occurs when an atom has a high electron affinity and is able to attract electrons from another atom with a lower electron affinity.

The process of ion formation is crucial in many chemical reactions, including the formation of salts from acids and bases and the conduction of electricity in electrolytes.

What are negatively charged ions called?

Negatively charged ions are called anions. In chemistry, an ion is an atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons. Anions are formed when an atom or molecule gains electrons, which results in a negative charge because electrons carry a negative charge. This process is known as electron gain or reduction. The opposite of an anion is a cation, which is a positively charged ion that is formed when an atom or molecule loses one or more electrons. Anions are crucial in various chemical reactions and are commonly found in solutions, such as the electrolytes in batteries or the salts dissolved in water.