The atomic number of an element represents the number of protons in the nucleus of an atom. In the case of uranium-235, which has an atomic number of 92, it means that there are 92 protons present in the nucleus.
To determine the number of neutrons in an atom, you can subtract the atomic number from the atomic mass of the isotope. The atomic mass of uranium-235 is approximately 235 atomic mass units (AMU).
Therefore, to calculate the number of neutrons in uranium-235, subtract the atomic number (92) from the atomic mass (235):
Number of neutrons = Atomic mass - Atomic number Number of neutrons = 235 - 92 Number of neutrons = 143
So, uranium-235 has 143 neutrons.