Bismuth 201 has 118 neutrons.
To determine the number of neutrons in any isotope of an element, you need two pieces of information: the atomic number (number of protons) of the element and the mass number of the specific isotope. The mass number is typically indicated after the element's name, such as "201" in Bismuth 201.
Understanding Atomic Structure
Every atom is defined by its number of protons, also known as its atomic number. For Bismuth (Bi), this number is consistently 83 across all its isotopes. This means that any Bismuth atom, regardless of its specific isotope, will always have 83 protons.
Here's a quick look at the fundamental properties of Bismuth:
| Property | Value |
|---|---|
| Name | Bismuth |
| Atomic Number | 83 |
| Number of Protons | 83 |
| Number of Electrons | 83 |
| Atomic Mass (average) | 208.98038 atomic mass units |
| Number of Neutrons (for common isotope) | 126 |
Note: The "Number of Neutrons: 126" listed above refers to the most common and stable isotope of bismuth, Bismuth-209. This is derived from its mass number (209) minus its atomic number (83), resulting in 126 neutrons.
Calculating Neutrons for Bismuth 201
The mass number of an atom represents the total count of protons and neutrons in its nucleus. It can be calculated using the formula:
Mass Number = Number of Protons + Number of Neutrons
For Bismuth 201:
- The Mass Number is 201 (as indicated by "Bismuth 201").
- The Number of Protons for Bismuth is 83.
Now, we can rearrange the formula to find the number of neutrons:
Number of Neutrons = Mass Number - Number of Protons
Let's apply this to Bismuth 201:
- Identify the Mass Number: Bismuth 201 has a mass number of 201.
- Identify the Number of Protons: Bismuth has 83 protons.
- Perform the Calculation:
Neutrons = 201 - 83
Neutrons = 118
Therefore, Bismuth 201 possesses 118 neutrons in its nucleus. This distinguishes it from other bismuth isotopes, such as Bismuth 209, which has 126 neutrons (209 - 83 = 126). Each isotope of an element shares the same number of protons but varies in its number of neutrons, leading to different mass numbers.
