 ## 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

# Subatomic Particles

The atom is composed of 3 subatomic particles:neutrons, protons, and electrons.

The Atom & Subatomic Particles

In terms of size, neutrons are the largest, protons are slightly smaller, and the electrons are the smallest.

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concept

## Subatomic Particles 5m
Play a video:
the three key subatomic particles share some key differences and similarities in their masses, and charges now associated with subatomic particles is a new term. AM you am you is shorthand for atomic mass unit and is used to calculate the relative mass of an atom or subatomic particle. When it comes to the term of am, you weaken related to a few different things. First of all, we're gonna say 1 a.m. U equals 1/12 the mass of a carbon Adam. Now that's the official definition of it. But more importantly than that, when it comes to us, we're gonna say also that 1 a.m. U. Is equal to a new term. Dalton shorthand for Dalton is d A. It's named after John Dalton. John Dalton is one of the fathers of chemistry. We learn that there are the other ones. They're also connected to the subatomic particles. But the first we're going to talk about here is John Dalton. Now, most importantly, we have here a purple box Anytime we have a purple box that tells you that this is something you should memorize. It could be a formula. It could be a conversion factor. It could be a definition if it's in a purple box. That means that's an indication that I need toe. Remember what this is now? There's a lot of numbers, a lot of terms within the chart below it, but none of it's in purple, which means you really don't have to memorize those portions. So again, if you see a purple box, that means memorize this 1 a.m. U. Is equal to 1.66 times 10 to the negative 27 kilograms. So that is our conversion factor, which will allow us to go from kilograms 2 a.m. U and vice versa. Now how does it relate to our three subatomic particles? Well, when talking about our three subatomic particles neutrons, protons and electrons so their actual masses. If we look at neutrons, it's 1.67493 times 10 to the negative kg. Protons are very, very close. They're 1.67262 times 10 to the negative 27. So if you look, this is this is four and this is to protons, even though they're neutral, are just a little bit heavier in mass than protons. And then we can see that protons and neutrons way a lot mawr than electrons. Electrons are 0.91 times 10 to the negative 27. Now what is this telling me? Well, we know that the neutrons and the protons are housed within the nucleus, right? And we know protons and neutrons way mawr than electrons. So that would tell me that a majority of the mass of an atom is in the nucleus of the atom. That's what these numbers were telling me. Now we can take our actual masses and convert them into relative mass. The relative mass is where am you? Comes into play. So here we'd say that the relative mass of the neutron comes out to 1.866 a. M u. The relative mass of the proton comes out to 1. to 7 a.m. u. And then finally the mass of the electron comes out 2.55 a. M u. So actual mass relative mass, it doesn't matter. We can still see that the neutrons wait just a little bit more than the protons and both the neutrons and protons way a lot mawr than our electrons. Now here we have our relative charges, things we've already known about the subatomic particles. We know that the neutrons have no charge, so the relative charge zero protons are plus one. Electrons are minus one, but let's convert that into actual charge, more returning it into actual charge. Another name for charge is cool ums. So we'll go into greater detail with this term of columns when we go into chapters on electoral chemistry. But that's not for several chapters later. Now, if we're converting relevant charge to actual charge, this comes out to still be zero. Because it has no charge for protons, this comes out as positive 1.60218 times, 10 to the negative 19 cool ums And then remember, electrons have the opposite sign opposite magnitude, so it be the same exact number, but with an opposite sign so negative of that value. So these are the key identities key information on the three sub atomic particles. Now, again, it's a lot of information before us, but remember, what's in the purple box is most important here. When we talk about the relative charges, we already know what those are. So I didn't put boxes around those That's basic knowledge that should we should all. Now, now that we've talked about key similarities and differences of the subatomic particles, let's move on to some questions.
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example

## Subatomic Particles Example 1 3m
Play a video:
So in this example question. It says, Oz me, Um, one of the densest elements on earth has an actual mass of 190.23 g according to the table above what is its value in terms of atomic mass units? All right, so if we take a look here, all our answers are given indulgence. Remember, Adult in is the same thing as an atomic mass unit. We're gonna start out with this given amount, So this is our given amount, and it is our responsibility to get to the end amount. So we need to get to this end. Amount now are given amount is 1 90 to 3 g, and we have to get to our end amount in Dalton's, which is the same thing as I am you now. In order to go from are given amount, tow our end amount, we have to utilize conversion factors. Now, the conversion factor we're gonna use here our first conversion factors Conversion factor one, we're first going to do a metric prefix conversion. We're gonna change grams to kilograms. We want to get rid of grams, so grams go here on the bottom kilograms go on top. Remember the coefficient of one goals on the side with the metric prefix meaning 1 kg is 10 to the three. Now that grams are on opposite levels, they cancel out, we'll have kilograms at the end. We have to change the kilograms because now we're going to say for conversion factor to our metric prefix above says that 1.66 times 10 to the negative kg is equal to 1 a.m. U. Remember an AM you and adult in are the same thing. So now our kilogram numbers cancel out, and we'll get our answer here as Dalton's can. So what's gonna be here? It's 1 90.23 divided by 10. divided by 1.6 times 10 to the negative. 27. Remember, something is written in scientific notation. Tow. Avoid any errors within your calculator. You should put it in parentheses. If you do this correctly, what you'll get initially. Well, what you get at the end is 1.15 times 10 to the 26 Dalton's or am. You remember they're interchangeable with one another. So if you look at our choices here. Which one matches up with that value? That would be option A. So here we're talking about conversion of grams 2 a.m. Your Dalton's. This is called dimensional analysis. We start out with are given amount. We have to get to our end amount and to get there, we utilize conversion factors here. We had to employ metric prefix conversion with conversion factor one and then use the metric used the conversion factor listed above for conversion. Factor to that takes us from kilograms to Dalton's or am you? So if you're a little bit rusty in terms of this, make sure you take a look at our videos on dimensional analysis, because this is the basic set up for any dimension analysis type of question.
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Problem

According to the table above, how many electrons are required to produce a charge of –2.0 C?

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Problem

If the charge and mass of one proton is 1.60218 x 10-19 C and 1.673 x 10-30 g respectively, what is the charge of 378 kg of protons? 