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

Worked example: Identifying an element from successive ionization energies | Khan Academy


2m read
·Nov 10, 2024

We are told that the first five ionization energies for a third period element are shown below. What is the identity of the element? So pause this video and see if you can figure it out on your own, and it'll probably be handy to have a periodic table of elements.

So before I even look at a periodic table of elements, let's make sure we understand what this table is telling us. This is telling us that if we start with a neutral atom of this mystery element, it would take 578 kilojoules per mole to remove that first electron to turn that atom into an ion with a plus one positive charge.

Then it would take another 1817 kilojoules per mole to remove a second electron, so to make that ion even more positive. After that, it would take another 2745 kilojoules per mole to remove the third electron. Then, to remove the fourth electron, it takes a way larger amount of energy. It takes 11,000 kilojoules per mole, and then the fifth electron takes even more: 14,842 kilojoules per mole.

For the first, second, and third, you do have an increase in ionization energy, but when you go to the fourth, the energy required to remove those is way higher. So to me, these look like you're removing valence electrons, and these look like you're removing core electrons.

One way to think about it is let's look at our periodic table of elements and look for a third period element that has three valence electrons. So we have our periodic table of elements. We want a third period element, so it's going to be in this third row. Which of these has three valence electrons?

Well, sodium has one valence electron, magnesium has two valence electrons, aluminum has three valence electrons. So one way to think about it is that first electron: it's a reasonable ionization energy. Then the second one, a little higher; then the third, a little bit higher than after that. But then the fourth, you're starting to go into the core. You're going to have to take an electron out of that full second energy shell, which takes a lot of energy.

So this is pretty clearly aluminum that is being described.

More Articles

View All
Dinosaurs 101 | National Geographic
(Dramatic music) (Roaring) - [Narrator] Probably no other creatures on the planet have struck as much fear and awe in our hearts as the dinosaurs. (Roaring) The earliest dinosaurs appeared about 245 million years ago during the Triassic Period, when most …
Private vs first class.
If you had the choice between flying private or flying first class, which would you choose? Private, 100% of the time. Flexibility, security, safety, quality of life, time. You can leave when you want to go, what airport you want to go to and from. It’s …
Why do billionaires buy used private jets?
Really super rich, why would you buy a pre-owned aircraft? You could say the same thing about somebody who’s not so rich but fairly well-to-do, and they buy a used car. Sometimes you want immediate satisfaction, and if you want immediate satisfaction, you…
Charlie Munger: How the Stock Market Really Works
[Music] Charlie Munger is commonly referred to as Warren Buffett’s right-hand man, but he’s actually a very clever, smart, successful investor in his own right. Back when he ran his investment partnership, he was able to generate 20% annual returns for a…
Indonesia's Coral Reefs - 360 | Into Water
Oceans are critical to keeping our global ecosystem in balance. They are home to hundreds of thousands of species, many of which are under threat. There are millions of people whose day-to-day survival depends on their continued health. [Music] My connec…
Why The First Computers Were Made Out Of Light Bulbs
[Derek] The modern era of electronics began with the light bulb but not in the way you might think. Early light bulbs consisted of a carbon filament sealed inside a glass bulb with a vacuum inside. When a potential difference was applied across the filame…