Nuclide Definition
The word “Nuclide'' was coined by an American Chemist named Truman P. Kohman in 1947. The term nuclide or nuclide is taken from the word nucleus. It is one of the nuclear species.
A nuclide is like an atom or nucleus but it differs from these two. It is characterized by a number of protons and neutrons.
In simple words, nuclide is a species of atom/nucleus. We describe it by the composition of its nucleus, by the number of protons, the number of neutrons, and the energy content.
On this page, you will learn about the nuclide, daughter nuclide, radioactive nuclide, parent nuclide, stable nuclides.
Nuclide Definition Physics
A nuclide is described by the mass number (A) and the atomic number (Z). For considering it distinct, a nuclide must have an energy content enough for a measurable lifetime, i.e., more than 10−10 seconds.
The term nuclide is not similar to an isotope, it is any member of a set of nuclides possessing the same atomic number but a different mass number.
For Example, Chlorine - 37 is the nucleus that comprises 17 protons and 20 neutrons, it is a different nuclide from the sodium - 23 nuclei having 11 protons and 12 neutrons, and chlorine - 35 nucleus of 17 protons and 18 neutrons.
Nuclide Symbols
Every nuclide has a chemical element symbol (E) in addition to an atomic number (Z), i.e., the number of protons with inside the nucleus, and a mass number (A), i.e., the whole number of protons and neutrons within the nucleus.
We express nuclides in the form of AXZ, where “A” is the total number of protons and neutrons, “Z” denotes the number of protons, and the difference between A and Z is the number of neutrons.
For instance, 37Cl17
Here, Cl signifies chlorine - 37
Let’s take another example:
The symbol for the “Li” element is given as;
7Li3
Nucleon number A = total number of protons and neutrons = 7
Proton number is equal to Z = total number of protons = 3
Li = the chemical element symbol (E)
Nuclides and Radioactive Decay
Nuclides are linked with radioactive decay and they can either be stable or unstable species.
Around 1,700 nuclides are known, of which 300 are stable and the rest radioactive.
In 1919, a British Physicist named Francis William Aston discovered the isotopes of the light elements (light elements are hydrogen, deuterium, helium (two isotopes), lithium, and trace amounts of beryllium) at the Cavendish Laboratory, using his new invention of the mass-spectrograph. By using his newly devised invention, he also discovered more than 200 stable nuclides.
Nuclide undergoes radioactive decay. Now, we will understand the science behind the parent nuclide, daughter nuclide, stable nuclides with a graph in detail.
Parent Nuclide and Daughter Nuclide
A parent nuclide is a determinate nuclide. It is an isotope whose radioactive decay products are sure daughter nuclides. It is a nuclide that decays into a daughter nuclide during the process of radioactive decay.
For example, Na-22 decays into Ne-22 after undergoing β + decay. Here, Na-22 is the parent nuclide and Ne-22 is the daughter nuclide.
Some More Examples are as Follows:
Tellurium or Te-131 after undergoing β + decay forms a daughter nuclide called Iodine - 131.
Here, Iodine - 131 is the parent nucleus of Xenon - 131.
Au - 208, after undergoing the nuclear reaction, produces Hg - 208.
The above examples on parent nuclide and daughter nuclide also express the relationship between these two.
You might have heard of isotopes, the two elements having the same atomic number but a different mass number. These isotopes are clearly matching with stable nuclides; let’s understand how:
Stable Nuclides
Out of 1,700 nuclides, 300 are non-radioactive or stable.
A stable nuclide is one that never undergoes radioactive decay. When we refer to such elements, we call them stable isotopes, while the nuclides that undergo radioactive decay are called the radioactive nuclides.
The below graph shows the stable nuclide with examples of elements:
(Image will be Uploaded Soon)
Do You Know?
Of the recognized chemical elements, eighty elements have at least one stable nuclide. These incorporate the primary eighty-two elements from hydrogen to lead, with the 2 exceptions, technetium (element 43) and promethium (element 61), that don't have any stable nuclides. As of December 2016, there had been a total of 253 recognized "stable" nuclides.
Examples of Isodiaphers
Example-1
Thorium - 234 = 90Th144
No of protons (Z ) = 90
Mass number (A) = no of neutrons + no of protons (Z)
Mass number = 234 and no of protons = 90
No of neutrons = A - Z = 234 - 90 = 144
Difference between neutrons and protons of Thorium = 144 - 90 = 54…(a)
Now, for Uranium-238 = 92U238
No of protons (atomic number Z) = 92
No of neutrons = 146
Difference between neutrons and protons of Uranium = 146 - 92 = 54….(2)
From eq (1) and eq (2), you can see that the difference between the neutrons and protons for Thorium-234 and Uranium-238 is the same.
Thus Th and U are examples of isodiaphers.
Example -2:
9F19 and Sodium 11Na23
For Fluorine:
No of protons = 9
Number of neutrons = 10 (19 - 9)
Difference = 10 - 9 = 1
For Sodium:
No of protons = 11 and
Number of neutrons = 12 (23 - 11)
So the difference is = 12 - 11 = 1
Here, you can notice that the difference between Fluorine and Sodium is the same, i.e. 1. Hence, fluorine and sodium are examples of isodiaphers.
FAQs on Nuclide
1. What is a nuclide in Physics?
A nuclide is a specific type of atomic nucleus, or an atom with that specific nucleus. It is uniquely identified by its atomic number (Z), which is the number of protons, and its mass number (A), which is the total number of protons and neutrons. Any nucleus with a measurable lifetime (greater than 10-10 seconds) is considered a distinct nuclide.
2. How is a nuclide represented using the standard symbol?
A nuclide is represented by the symbol AXZ, where:
- X is the chemical symbol of the element.
- Z is the atomic number (number of protons).
- A is the mass number (total number of protons and neutrons).
For example, the nuclide Carbon-14 is written as 14C6, indicating it has 6 protons and (14-6) = 8 neutrons.
3. What is the main difference between a nuclide and an isotope?
The main difference lies in their scope. A nuclide refers to any specific nucleus with a defined number of protons and neutrons. Isotopes, on the other hand, are a specific group of nuclides. They are nuclides that share the same atomic number (Z) but have different mass numbers (A), meaning they belong to the same element but have a different number of neutrons. For example, 12C6 and 14C6 are two different nuclides, and they are also isotopes of carbon.
4. How does the concept of a nuclide differ from that of an atom or a nucleus?
A nucleus is the central part of an atom containing protons and neutrons. An atom is a neutral entity consisting of a nucleus and its surrounding electrons. A nuclide is a more specific term that characterises the nucleus by its exact proton count, neutron count, and energy state. While we often use "nuclide" to refer to a specific nucleus, it formally defines a nuclear species. The key is its unique nuclear composition.
5. What are parent and daughter nuclides? Explain with an example.
In radioactive decay, a parent nuclide is an unstable nuclide that undergoes decay to transform into another nuclide. The resulting nuclide is called the daughter nuclide. For example, in the beta decay of Sodium-22, 22Na is the parent nuclide. It decays into 22Ne, which is the daughter nuclide. This process often continues in a decay chain until a stable nuclide is formed.
6. What makes a nuclide stable or unstable (radioactive)?
The stability of a nuclide is determined by the balance between its number of protons and neutrons, often analysed through the neutron-to-proton ratio (N/Z).
- For lighter elements, stable nuclides have an N/Z ratio close to 1.
- For heavier elements, more neutrons are needed to overcome the strong electrostatic repulsion between protons, so the N/Z ratio for stable nuclides gradually increases to about 1.5.
Nuclides with a ratio that falls outside this "band of stability" are generally unstable and undergo radioactive decay to achieve a more stable configuration.
7. Besides isotopes, what other relationships exist between different nuclides?
Besides isotopes, different nuclides can be related in several other ways based on their composition:
- Isobars: Nuclides with the same mass number (A) but different atomic numbers (Z). Example: 40Ar and 40Ca.
- Isotones: Nuclides with the same number of neutrons (N) but different atomic numbers (Z). Example: 39K (20 neutrons) and 40Ca (20 neutrons).
- Isodiaphers: Nuclides that have the same difference between their number of neutrons and protons (N - Z). Example: 238U (N-Z = 146-92 = 54) and 234Th (N-Z = 144-90 = 54).
