There are 21 neutrons in the isotope K-40.
Understanding Potassium-40 (K-40)
Potassium-40, often denoted as K-40 or $^{40}$K, is a naturally occurring radioactive isotope of potassium. Its atomic structure is defined by the number of protons and neutrons it contains.
Here's a breakdown of its key nuclear components:
| Component | Count |
|---|---|
| Protons (Z) | 19 |
| Neutrons (N) | 21 |
The number of protons (atomic number, Z) uniquely identifies an element. All potassium atoms, regardless of their isotope, have 19 protons. The mass number of an isotope (the '40' in K-40) represents the total count of protons and neutrons in its nucleus.
To determine the number of neutrons in any isotope, you can use the simple formula:
Neutrons = Mass Number - Protons
For K-40:
Neutrons = 40 (Mass Number) - 19 (Protons)
Neutrons = 21
This specific combination of 19 protons and 21 neutrons gives K-40 its unique nuclear properties, including its radioactivity and long half-life, which makes it important in various scientific fields like geology (potassium-argon dating) and biology.
For more detailed information, you can refer to the Potassium-40 Wikipedia page.
