Subatomic Particles - Online Tutor, Practice Problems & Exam Prep

Understanding the fundamental components of an atom is crucial for grasping the basics of chemistry. Atoms are composed of three subatomic particles: neutrons, protons, and electrons. Neutrons and protons, which are approximately equal in mass, are significantly heavier than electrons and are located in the atom's nucleus, accounting for most of an atom's mass. The mass of these particles is measured in atomic mass units (amu) or Daltons (Da), with 1 amu defined as 1/12 the mass of a carbon-12 atom. This unit of measure translates to:

$1.66\times {10}^{-27}\text{kilograms}$

When it comes to charge, protons carry a positive charge (+1), electrons have a negative charge (-1), and neutrons are neutral (0). The actual charge of a proton or electron is:

$\pm 1.60218\times {10}^{-19}\text{coulombs}$

This understanding of the mass and charge of subatomic particles is essential for delving into more complex topics in chemistry, such as electrochemistry and the behavior of atoms in different states and reactions.

Subatomic Particles

The three key subatomic particles share some key differences and similarities in their masses and charges. Now associated with the subatomic particles is a new term AMU. AMU 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 AMU, we can relate it to a few different things. First of all, we're going to say one AMU equals 112 the mass of a carbon 12 atom. Now that's the official definition of it.

But more importantly than that, when it comes to us, we're going to say also that one AMU is equal to a new term. Dalton, shorthand for Dalton, is DA. It's named after John Dalton. John Dalton is one of the fathers of chemistry. We'll 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 to 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 one. AMU is equal to 1.66×10-27 kg. So that is our conversion factor which will allow us to go from kilograms to AMU 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 1.67493×10-27 kg. Protons are very, very close, they're 1.67262×10-27 kg. So if you look, this is 4 and this is 2. 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 weigh a lot more than electrons. Electrons are 0.00091×10-27 kg.

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 weigh more 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 are telling me. Now we can take our actual masses and convert them into relative mass. The relative mass is where AMU comes into play. So here we'd say that the relative mass of the neutron comes out to 1.00866 AMU. The relative mass of the proton comes out to 1.00727 AMU and then finally the mass of the electron comes out to 0.00055 AMU.

Actual mass, relative mass, it doesn't matter. We can still see that the neutrons weigh just a little bit more than the protons, and both the neutrons and protons weigh a lot more than our electrons. Now here we have our relative charges, things we've already known about these subatomic particles. We know that the neutrons have no charge, so their relative charge is 0. Protons are plus one. Electrons are -1. But let's convert that into actual charge when we're turning it into actual charge. Another name for charge is coulombs.

So we'll go into greater detail with this term of coulombs when we go into chapters on electrochemistry, but that's not for several chapters later. Now, if we're converting relative charge to actual charge, this comes out to still be 0 because it has no charge. For protons, this comes out as +1.60218×10-19 C. And then remember, electrons have the opposite sign, opposite magnitude, so it'd 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 subatomic 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 know. Now that we've talked about key similarities and differences of the subatomic particles, let's move on to some questions.

Subatomic Particles Example 1

So In this example question, it says Osmium, one of the densest elements on earth, has an actual mass of 190.23g 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, a Dalton is the same thing as an atomic mass unit. We're going to 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. Our given amount is 190.23g. And we have to get to our end amount in Dalton's, which is the same thing as AMU. Now in order to go from our given amount to our end amount, we have to utilize conversion factors. Now the conversion factor we're going to use here. Our first conversion factor is conversion factor 1. We're first going to do a metric prefix conversion. We're going to 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 goes on the side with the metric prefix, meaning 1K is 10 to the three.

Now that grams are on opposite levels, they cancel out and we'll have kilograms at the end. We had to change the kilograms because now we're going to say for conversion factor 2, our metric prefix above says that

1.66 × 10 - 27 kg = 1 AMU

And remember, an AMU and a Dalton are the same thing. So now our kilogram numbers cancel out and we'll get our answer here as Dalton's. So what's going to be here? It's

190.23 10.33 / 1.6 × 10 - 27

Remember, if something is written in scientific notation, to 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'll get at the end is

1.15 × 10 26 Daltons or AMU

Remember, they're interchangeable with one another. So if we 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 to AMU or Daltons. This is called dimensional analysis. We start out with our 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 use the conversion factor listed above for conversion factor 2. That takes us from kilograms to daltons or AMU. 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 setup for any dimensional analysis type of question.

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

• A. 1.3 × 10¹⁹ electrons
• B. 2.0 × 10¹⁹ electrons
• C. 4.2 × 10²⁰ electrons
• D. 8.5 × 10²⁰ electrons

If the charge and mass of one proton is 1.60218 x 10^-19 C and 1.673 x 10^-24 g respectively, what is the charge of 378 kg of protons?

• A. 5.24 × 10¹³ C
• B. 9.07 × 10¹⁴ C
• C. 4.11 × 10¹⁵ C
• D. 3.62 × 10¹⁰ C

Here’s what students ask on this topic:

What are subatomic particles?

Subatomic particles are the smaller constituents of an atom, which is the basic unit of matter. These particles include protons, neutrons, and electrons. Protons and neutrons form the nucleus at the center of an atom, while electrons orbit around the nucleus in various energy levels.

Protons carry a positive electric charge, and their number in an atom's nucleus defines the chemical element's atomic number. Neutrons have no electric charge and contribute to the mass of an atom; they also play a key role in the stability of the nucleus. Electrons, which are negatively charged, are much lighter than protons or neutrons and are responsible for the chemical properties and reactions of an atom because they are involved in forming chemical bonds.

Beyond these three well-known particles, there are even smaller particles called quarks, which make up protons and neutrons, and leptons, which include the electron and its neutrino. These particles are fundamental in the Standard Model of particle physics, which is the theory describing the electromagnetic, weak, and strong nuclear interactions.

What subatomic particles are found in the nucleus?

The nucleus of an atom contains two types of subatomic particles: protons and neutrons. Protons are positively charged particles, and the number of protons in the nucleus determines the atomic number of an element, which defines the type of element it is. Neutrons, on the other hand, have no electric charge – they are neutral. The presence of neutrons contributes to the atomic mass of the atom and can vary in number among atoms of the same element, leading to the formation of different isotopes. Both protons and neutrons are collectively referred to as nucleons. They are held together in the nucleus by a strong nuclear force, which is much stronger than the electromagnetic force that repels the positively charged protons from each other.

How many subatomic particles are there?

Subatomic particles are the building blocks of atoms and come in various types, primarily categorized as fermions and bosons. Fermions include quarks and leptons, while bosons include force carrier particles like photons and gluons.

Quarks come in six 'flavors': up, down, charm, strange, top, and bottom, and they combine to form protons and neutrons. Leptons include the electron, muon, tau, and their corresponding neutrinos.

Bosons, on the other hand, are particles that mediate the fundamental forces of nature. The photon is the carrier of the electromagnetic force, the W and Z bosons are responsible for the weak force, gluons mediate the strong force, and the Higgs boson is associated with the Higgs field that gives particles mass.

In total, the Standard Model of particle physics identifies 17 fundamental subatomic particles: 6 quarks, 6 leptons, and 5 bosons. However, there are many more composite particles and resonances that arise from combinations of these fundamental particles, such as protons and neutrons (which are made of quarks). Additionally, there may be other subatomic particles not yet discovered that could exist beyond the Standard Model.

What are the three subatomic particles?

The three subatomic particles that form an atom are protons, neutrons, and electrons. Protons are positively charged particles found in the nucleus of an atom. The number of protons in the nucleus determines the atomic number of an element and thus its identity. Neutrons, which are neutral particles with no charge, are also located in the nucleus. They contribute to the mass of the atom and can affect the stability of the nucleus. Electrons are negatively charged particles that orbit the nucleus at various energy levels, often referred to as electron shells or clouds. The interactions between electrons and other atoms play a crucial role in chemical reactions and bonding. The balance between the number of protons and electrons in a neutral atom is equal, resulting in no overall charge.

What are the charges and relative masses of subatomic particles?

Subatomic particles, which are the building blocks of atoms, include protons, neutrons, and electrons. Each type of particle has a distinct charge and relative mass.

Protons carry a positive charge, with a relative charge of +1. Their relative mass is approximately 1 atomic mass unit (amu), which is about $1.6726\times {10}^{-27}\text{kilograms}$.

Neutrons have no electric charge, meaning they are neutral, with a relative charge of 0. They are slightly more massive than protons, with a relative mass close to 1 amu, approximately $1.6749\times {10}^{-27}\text{kilograms}$.

Electrons have a negative charge, with a relative charge of -1. However, they are much lighter than protons and neutrons, with a relative mass of roughly $\frac{1}{1836}$ amu or about $9.1094\times {10}^{-31}\text{kilograms}$.

It's important to note that in the context of atoms, the masses of protons and neutrons are almost equal and significantly larger than the mass of an electron, which is why the bulk of an atom's mass is concentrated in its nucleus, composed of protons and neutrons.