The relation between the number of protons and the number of neutrons in an atom can vary depending on the specific element and is determined by its isotope.
Isotopes are atoms of the same element that have the same number of protons but differ in the number of neutrons. Since the number of protons determines the element's identity, isotopes of the same element have the same atomic number (number of protons).
The number of neutrons, however, can vary within a given element, resulting in different isotopes. Isotopes are denoted by the element's symbol followed by a hyphen and the mass number, which represents the total number of protons and neutrons in the atom.
For example, let's consider the element carbon (C). The most common isotope of carbon is carbon-12 (written as C-12), which has 6 protons and 6 neutrons. However, carbon can also exist in the form of carbon-13 (C-13) with 6 protons and 7 neutrons, as well as carbon-14 (C-14) with 6 protons and 8 neutrons.
The number of neutrons in an atom can affect its stability, nuclear properties, and reactivity. Isotopes with different numbers of neutrons can have slightly different physical and chemical properties but share similar chemical behavior due to their identical number of protons and electrons.
In summary, the number of protons determines the element's identity, while the number of neutrons can vary within a given element, resulting in different isotopes.