For radioactive isotopes like uranium 235 what is the 235 indicate – Free 6B
Understanding the Notation in Uranium-235
Question:
For a radioactive isotope like Uranium-235, what does the number 235 indicate?
- Atomic mass
- Atomic number
- Half-life
- Isotope number
Answer:
The number 235 represents the mass number.
Detailed Explanation:
In the notation Uranium-235 (often written as ²³⁵U), the number 235 refers to the mass number.
The mass number is the total number of particles in the nucleus of an atom, specifically:
- Protons (atomic number)
- Neutrons
For Uranium (U):
- The atomic number is 92, meaning there are 92 protons in the nucleus.
- The mass number is 235, so the number of neutrons is:
Neutrons = Mass number − Atomic number = 235 − 92 = 143
This distinguishes Uranium-235 from other isotopes of uranium (like Uranium-238), which have different numbers of neutrons but the same number of protons.
Summary: The number 235 in Uranium-235 is its mass number, which equals the sum of protons and neutrons in the nucleus.