yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Worked example: calculating ion charge | High school chemistry | Khan Academy


2m read
·Nov 10, 2024

So we're asked what is the charge of a calcium ion with 18 electrons. So pause this video and see if you can work that on your own. I will give you a little bit of a tip: a periodic table of elements might be useful to see where calcium sits on that periodic table of elements.

So why don't you pause this video and see if you can figure out the charge of that calcium ion?

All right, so what defines the element is actually how many protons it has, and that's what we have right over here. Its atomic number is 20. That's how many protons it has. So we could say the number of protons, which provide positive charge, is 20.

And then we know the number of electrons is 18. That's negative charge, so I'll just write it here, number of electrons. All right, I'll abbreviate it right over there or I'll shorten it; that is 18. And this has a negative charge.

So if you want to know the net charge, you take the number of protons, the positive charge, and subtract out the number of electrons. And so that leaves you with a positive two charge. Twenty minus eighteen is positive two, and we will denote that with a 2 plus.

So some people might write this as calcium two plus, just like that, to show that it is a calcium ion. It's likely the situation maybe where calcium originally had 20 electrons and 20 protons, so then it would not be an ion; it would just be a neutral atom. But maybe it lost those, it lost two of those electrons, and so then it got a positive two or a two plus charge.

Let's do another example over here. So if I were to ask you what is the charge of an ion that has seven protons, eight neutrons, and ten electrons, pause this video and think about what that would be.

Well, we can confirm that that indeed would be an ion because it has a different number of protons than it does electrons. And if you want to figure out the charge, you just take the number of protons, seven, which are the positive charges, and you subtract out the negative charges. That's why you're subtracting; you subtract out the electrons.

So seven minus ten would be equal to negative three. And so I would say you'd often denote that as saying a 3 minus charge. And if you wanted to write down what that ion is, we can go back to the periodic table of elements.

We can see that if you have seven protons, by definition, you are talking about nitrogen. So that would be a nitrogen ion that you would denote like that: it has a negative 3 or 3 minus charge.

More Articles

View All
Is Light a Particle or a Wave?
There is a video on YouTube which has Deutsch explain the famous quantum double slit experiment, which is about particle-wave duality. Is light a particle, or a wave? You pass it through a slit depending on whether there’s an observer and interference or …
Got Bees? Meet a Swarm Chaser Up for the Challenge | Short Film Showcase
[Music] [Music] [Music] Hello! Oh gosh, do you have some bees? Okay, so are the bees outside? Are they hanging on a tree, or like, where are the bees at? You know, as a child, I spent a lot of time crafting and making miniatures. I think that that ties i…
Sewage treatment | Aquatic and Terrestrial Pollution | AP Environmental Science | Khan Academy
This is my cat, Rubiks. One of the many amazing things about Rubiks is that he naturally works to keep himself clean. His barbed tongue is really good at getting rid of the dust and dirt that he gets in his fur every day, but sometimes he needs a little h…
Sexy Storm Troopers AND Tron Dogs: IMG! episode 10
Cats and dogs cooperating and zombie versions of Master Chief, Princess Peach, and Pikachu. It’s episode 10 of IMG. Here’s something for people who like silly bands but also like to keep their wrist jewelry x-rated. And how can I keep my data safe? Oh, I…
Medical School Exam Week Vlog | Med School Diaries
This video is sponsored by Psych2Go. Psych2Go is an amazing channel for those who are interested in mental care and different things about mental health, and I’m sure that a lot of you guys are following them. Actually, don’t forget to check out their vid…
HOW TO GET 1000 SUBSCRIBERS ON YOUTUBE IN 2022
What’s up you guys? It’s great I’m here! So really quick, before I get into the video, is really fun YouTube experiment. Hit the like button and comment anything down below for the almighty YouTube algorithm. The reason for this is because from all the r…