Perhaps one of the concepts that chemistry focuses on the most is the atom. In fact, the atom was once known as the smallest form of matter, but it turned out that it contained protons, neutrons and electrons. Just when these were the smallest particles, other subatomic particles emerged. However, we can say that the fundamental particles of the atom are protons and neutrons, and the number of nucleons, known as the mass number, represents exactly these parts.
We have more or less understood what the atomic number is, but do not ask where this nucleon number, that is, the mass number, came from. Because each part of the atom is actually extremely important to determine its type. In fact, if these values are different, it reveals that that atom is a completely different type. Let’s take a closer look at frequently asked questions such as what is the mass number, that is, the nucleon number, and how to find it.
For those who don’t know, let’s start from the basics; What is an atom?
In the universe we know, the smallest building block that carries the physical and chemical properties of matter is called an atom. There are protons and neutrons in the nucleus of the atom, and there are electrons surrounding this nucleus. The type of atom is determined by the number of protons, neutrons and electrons the atom has.
So what is a nucleon?
We said that the atom consists of a nucleus filled with protons and neutrons and electrons surrounding it. This proton and neutron have the common name nucleon. It is considered the fundamental particle of the atomic nucleus. In fact, it is not a single particle; it is a compound particle consisting of quarks and gluons. They are part of the baryon class of subatomic particles.
What is the number of nucleons, also known as mass number?
In fact, when you define the nucleon, it becomes more or less clear what the number of nucleons is. The number of nucleons, called mass number, is the total value of the number of protons and neutrons, that is, nucleons, in the nucleus of an atom.
How to find the number of nucleons with the formula that you can apply most easily?
- Mass number i.e. number of nucleons = A
- Number of protons = Z
- Number of neutrons = N
- A = Z + N
- well
- Mass number i.e. number of nucleons = number of protons + number of neutrons
Let’s see how to find the mass number, that is, the number of nucleons, through examples:
Example 1:
- The helium atom has 2 protons and 2 neutrons.
- A = Z + N
- A = 2 + 2
- A = 4
- So the nucleon number of the helium atom is 4
Example 2:
- The oxygen atom has 8 protons and 8 neutrons.
- A = Z + N
- A = 8 + 8
- A = 16
- So the number of nucleons of the helium atom is 16.
Example 3:
- The sodium atom has 11 protons and 12 neutrons.
- A = Z + N
- A = 11 + 12
- A = 23
- So the number of nucleons of the helium atom is 23.
Example 4:
- The chlorine atom has 17 protons and 18 neutrons.
- A=Z+N
- A = 17 + 18
- A = 35
- So the number of nucleons of the helium atom is 35.
Okay, but what happens when we find the mass number? What does the nucleon number indicate?
In fact, the most important value in an atomic particle is the number of protons. Because the type of atom is determined accordingly. The number of nucleons is also a different factor that determines this type. For example, if the number of protons in an atom changes, a completely different element emerges. If the number of electrons changes, iodine emerges. Even if the number of neutrons changes, an isotope emerges. So the number of nucleons is extremely important to determine the type of atom.
There is also the atomic number:
Atomic number refers to the number of protons in the nucleus of an atom. In chemical elements that are neutral, the number of electrons and protons is equal, but there are also different states. The number of protons we show as Z in our formula also represents the atomic number. We have previously explained the details about the atomic number in our article here.
In the atomic context, everything is interconnected:
You may be a little confused because the atom has many different sub-particles, but the most basic feature that determines the type of atom, that is, defines it characteristically, is actually the number of protons it contains in its nucleus. The number of protons, which is also the atomic number, allows you to quickly understand which atom you are looking at.
The number of neutrons varies. For this reason, while the number of protons gives an unchanging identity to the atom as the atomic number, the number of nucleons, that is, the mass number, is not exactly such a value. We have already said that atomic forms that vary in terms of the number of neutrons are called isotopes.
As we gave the formula above, the mass number, that is, the number of nucleons, is the sum of the number of protons and the number of neutrons in the atomic nucleus. Let’s say you know the atomic number of an atom, that is, the number of protons and nucleons. To find the number of neutrons of this atom, simply subtract the number of protons from the number of nucleons, that is, the mass number.
We answered the question of how to find the mass number, that is, the number of nucleons, which is one of the most basic topics in chemistry, and explained the formula that you can apply through examples. Of course, the atom is a subject as deep as an ocean that you will get lost in when you dive into it, but in this article we aimed to provide basic information only for those who meet it for the first time.
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