Question

How many protons and neutrons are in uranium-$235$?

Answer 1

Uranium-$235$ is a radioactive element. The protons and neutrons together make the nucleus of the atom. A neutral atom is known to contain an equal number of protons and electrons.

Complete answer:
Before determining the protons and neutrons at first we have to be aware of a few terms related to the structure of an atom. The nucleus of an atom is the central part of an atom which constitutes most of the space inside the atom. The nucleus is surrounded by electrons which are moving around the nucleus and are negatively charged.
The nucleus is composed of neutrons and protons of which the proton is positively charged ions and the neutrons are neutral species. So the nucleus of an atom possesses positive charge. Thus a neutral atom will have an equal number of protons and electrons.
The next is the representation of an atom along with the atomic number and the mass number. The atomic number of an atom is referred to as the number of protons present in an atom. Actually the elements in the modern periodic table are placed based on increasing atomic number. The atomic number is represented by a subscript of the number besides the element symbol.
The mass number indicates the total number of protons and neutrons in the nucleus of an atom. The mass number is represented by the superscript of the number besides the element symbol.
The uranium element is denoted as $U_{92}^{235}$ , where $235$ is the mass number and $92$ is the atomic number. Hence the number of protons = the atomic number = $92$.
The number of neutrons = mass number – number of protons =$235 - 92 = 143$.

Note:
The protons and the neutrons are collectively called nucleons. The element uranium is a radioactive species. The other isotope has mass number $238$. So both the isotopes have the same number of protons but different numbers of neutrons.