Uranium-235 is used in nuclear fission. Determine the number of protons and the number of neutrons in uranium-235 and write its symbol in the form AZX.

Isotopes are variants of a particular chemical element that share the same number of protons, which means they have the same atomic number, but they possess a different number of neutrons. As a result, isotopes have different mass numbers. An example of isotopes is provided by Uranium, which has several isotopes, including Uranium-235 and Uranium-238.

These isotopes have unique properties that affect their stability and the types of reactions they can undergo. For instance, Uranium-235 is a key isotope used in nuclear reactors because it is fissile, meaning it can sustain a chain reaction of nuclear fission. Understanding isotopes is crucial as they have varied applications ranging from medicine, such as in cancer treatment, to energy production in nuclear power plants.

The atomic number is a fundamental property of an element, symbolized by the letter 'Z.' It represents the number of protons in the nucleus of an atom, which determines the element's identity. For example, all uranium atoms have an atomic number of 92, which is a unique identifier for the element uranium across all its isotopes.

Since the number of protons defines the type of element, elements on the periodic table are arranged in increasing order of atomic number. The atomic number also indirectly tells us about the number of electrons in a neutral atom, which equals the number of protons, maintaining overall charge balance.

The number of neutrons in isotopes is a distinguishing feature that offers variety in atomic mass without changing the elemental identity. Since isotopes of an element have the same atomic number, they differ only in the number of neutrons. To calculate the number of neutrons in an isotope, you subtract its atomic number (the number of protons) from its mass number.

For example, in Uranium-235, the atomic number is 92, and the mass number is 235. Thus, by subtracting, we find Uranium-235 has 143 neutrons. The number of neutrons contributes to the stability of the nucleus, with certain neutron-proton ratios conferring more stability to the nucleus.

Nuclear chemistry is the subfield of chemistry dealing with radioactivity, nuclear processes, and transformations in the nuclei of atoms. One key process in nuclear chemistry is nuclear fission, where a heavy nucleus like Uranium-235 splits into lighter nuclei, releasing a significant amount of energy. This energy is harnessed in nuclear power plants to generate electricity.

In the case of Uranium-235, when a neutron strikes the nucleus, it can cause the nucleus to become unstable and split. This splitting releases additional neutrons that can then induce fission in other Uranium-235 nuclei, creating a chain reaction. Understanding these nuclear reactions is essential for the safe and efficient operation of nuclear facilities and has implications in areas ranging from energy policy to the development of nuclear medicine.