Uranium-235 Nucleus Composition

The question asks about the components found within the nucleus of a specific isotope of uranium, known as uranium-235.

Atoms are made up of protons, neutrons, and electrons. Protons and neutrons are located in the central part of the atom called the nucleus, while electrons orbit the nucleus.

Each element is defined by the number of protons in its nucleus, which is called the atomic number, represented by $Z$. The mass number, represented by $A$, is the total number of protons and neutrons in the nucleus.

Uranium-235 Properties

For Uranium (U), the atomic number ($Z$) is always 92. This means any uranium atom has 92 protons in its nucleus.

The number 235 in "uranium-235" is the mass number ($A$). This number tells us the total count of protons and neutrons in the nucleus of this particular uranium isotope.

The relationship between mass number ($A$), atomic number ($Z$), and the number of neutrons ($N$) is given by the formula:

$$A = Z + N$$

For uranium-235:

• Mass number ($A$) = 235
• Atomic number ($Z$) = 92 (number of protons)

We can find the number of neutrons ($N$) using the formula:

$$N = A - Z$$

$$N = 235 - 92$$

$$N = 143$$

So, a nucleus of uranium-235 contains 92 protons and 143 neutrons.

The total number of particles in the nucleus is the sum of protons and neutrons, which is $92 + 143 = 235$. This is equal to the mass number.

Analyzing the Options

• Option 1: 235 neutrons

  This is incorrect. The number of neutrons is 143.

• Option 2: 235 protons

  This is incorrect. The number of protons is 92, which is the atomic number of Uranium.

• Option 3: A total of 235 protons and neutrons

  This is correct. The total number of protons (92) and neutrons (143) is $92 + 143 = 235$, which is the mass number of uranium-235.

• Option 4: 235 electrons

  This is incorrect. Electrons are not found in the nucleus; they orbit it. In a neutral atom, the number of electrons equals the number of protons (92), not 235.

Based on the analysis, the nucleus of uranium-235 contains a total of 235 protons and neutrons.