Hi, how's everyone doing today? I hope everyone's doing well. Today we're going to talk about shells or energy levels, subshells, and orbitals. When trying to understand the structure of an atom with all its components including protons, neutrons, and electrons, it was pretty difficult to imagine the actual structure of where this all came together.
So scientists created a simplified way to address and visualize how these components looked. It's called the Bohr model. This will look very familiar to you, and that's because it's doing its job, being simple.
This model shows electrons circling around a nucleus the same way the planets orbit the sun. Since the old saying goes, opposites attract, it definitely holds true in this case that the negative charges in the electrons are very much so attracted to the positive charges of the protons in the nucleus. And to keep electrons from actually snapping together with the proton counterparts, electrons move at a constant motion around the atoms to avoid that. Again, this is somewhat similar to how planets orbit the Sun. However, if you were to just add the right amount of energy to an electron, then it would move to a higher level further away from the nucleus, keeping its orbiting distance even further from the nucleus.
Here you can see that there are protons and neutrons in the very center, which we'll call the nucleus, while electrons are orbiting around the center. Again, opposite charges from the electrons and protons attract, and if we wanted to pull the electrons further away from the protons, we would have to inject more energy into electrons. These circles are sometimes known as energy levels. The further away you want your electrons, the more energy it takes.
These circles that the electrons orbit around are referred to as shells or energy levels. Electrons located in the outermost circles have higher energy because it takes more effort to move the electrons. and more energy to pull electrons away from the center.
We have labeled each of these circular lines, aka energy levels, simply as 1, 2, 3, and etc. Just FYI, the technical term for the numbers in these energy levels is called the principal quantum numbers. We use the letter N to represent the different levels. The higher the N level, the further away it is from the nucleus, and the smaller the N level, the closer the energy level is to the nucleus.
Also, the energy level closest to the nucleus is valued at n equals 1. Remember, this is Bohr's model, a simplified representation of the atom and all its parts. As you can see, the principal quantum number n is equal to 1, then 2, then 3, and so on, as the amount of energy is injected to push the elements further and further out. The electrons occupy lines circling around the nucleus.
Sometimes you'll see that K, L, M and N are used instead of 1, 2, 3, and 4. But let's refer to them as numbers because it's just easier that way. And as you can see, the further away you move from the nucleus, the energy increases. Now each energy level, again, aka shells, can only hold a specific number of electrons total for that example. The first energy level can hold up to 2 electrons.
The second can hold up to 8. The third... is up to 18 and so on. There's actually a really simple formula to determine how many electrons an energy level can hold, but we'll talk about that later on.
Okay, this is the nucleus right here in the center and the electrons surrounding it. Notice that I mentioned earlier that the first shell or energy level has two electrons, the second has eight, and the third and last shell on this picture has a total of 18 electrons that can occupy that space. It's a pretty good representation here since The further out the circles are, the more space we have to add electrons.
You might be asking, or at least I hope you're a bit curious about this, what about the fourth shell? How many electrons can that carry? Going back to what I mentioned earlier, there's a very, very simple formula that allows us to predict the number of electrons that can fit into a shell. The formula is simply 2n squared.
See, 2n squared would equal the maximum number of electrons that can fit in the shell. Using this formula, we can tell how many electrons will inhabit everything from the first to even the fourth shell. Let's take a closer look at this formula.
The n there refers to the shell or energy level number. Basically, if we were to ask how many electrons are in the first shell, n would be 1. How many electrons are in the second shell, n would be 2, and so on. Simple enough?
We already know from this video so far how many electrons inhabit energy levels 1 through 3. Let's find out how many electrons can fit into the fourth shell. Since n equals 4, let's replace n with 4. And according to the order of operations rule in mathematics, there are two operations going on here. One is to square and one is to multiply. Since the order of operations rule applies, it tells us to square first, then multiply. So the shell number 4 is squared, which is then equal to 16. And then we simply multiply 16 to 2 and the answer is 32 electrons.
That is the maximum number of electrons that can be held in the fourth shell. Let's confirm this by figuring out the maximum electrons the second shell can carry. Again, the second shell would make that n equals 2. Now, if we calculated 2 squared, then we get 4. And 4 multiplied by 2 is 8. Fantastic.
It works. Okay, let's move on to subshells. Try and guess the relationship between shells and subshells.
If you guess that subshells are pretty much smaller shells within normal shells, you're kind of halfway there. And like always, we need to label these things. So what do scientists do? They give sub-shells letters to reference itself as a sub-shell.
You're going to have to remember this, but I'll try to explain it in a way that's simple to understand. So within each energy level, or shell, there are sub-levels, or sub-shells. And fortunately for us, there are only four types. S, P, D, and F.
This is a silly way to remember it, but I'll just show you guys how I remembered it. Look at your keyboard on your computer. Just take notice where those letters are and how you would type S, P, D, F. That's basically it.
Whenever I try to remember these letters, I just remember the keystrokes I make. It's kind of weird, but that's how I learned it. So if you look at the table, I like to think of it as an award system.
On level 1, or N equals 1, you are given an S. Once you move to level 2, you already have an S and are given the letter P. If you continue on to become level 3, you got the S, P, and D. Now, one pro tip is just to notice how the n number actually equals how many sublevels you have. It's a neat little trick to keep in mind when you're trying to remember this.
Now, within each lettered sublevel, there's something we call orbitals. Orbitals are pretty much precisely where you find the electrons, 90% of the time. Each orbit can hold up to two electrons.
Remember that, two electrons. Sublevel S has one orbital. Sub-level P has 3 orbitals. Sub-level D has 5 orbitals. And F has 7 orbitals.
It's just odd numbers there, from 1, 3, 5, and 7. Since each orbital can hold up to 2 electrons, that would mean that sub-level S, with its 1 orbital, has 2 electrons. While P has 3 times 2, which is 6 electrons. D has 5 times 2. which is 10 and f has 7 times 2 which is 14 electrons that it can hold in that single sub level keep in mind that these are sub shells not shells themselves depending on the level of the shells it can contain more than one sub shell like how shell number four has sub shells s p d and f i tried to think of a way to explain this in a broad perspective and i think the best way to represent how this all fits together is by drawing out a tree-like diagram.
The top row represents the energy levels 1, 2, 3, and 4. Beneath that are the sublevels of S, P, D, and F. Notice again how each progression of the energy levels contains one more sublevel letter than the previous one did. The next row underneath is the orbitals.
Each S has one orbital. Each P has three. Each D has five.
and each f has seven orbitals. Finally, if you recall, each orbital can hold up to two electrons. So we multiply each orbital by two and we get our total electrons that each sub-level can contain. The very bottom row shows the total number of electrons that can possibly fit in each energy level.
And that's it for now. Thanks for joining me again. Until next time, remember to like, subscribe, and share.
Have a good one.