Three radon isotopes have \(125,134,\) and 136 neutrons. Write the symbol for each.

Understanding isotope notation is essential when studying chemistry, especially when dealing with different atoms of the same element.
An isotope notation is a written form that denotes a particular isotope of an element. It consists of the element's symbol, the atomic number as a subscript, and the mass number as a superscript. For example, in the case of radon isotopes with mass numbers of 211, 220, and 222, the notations are _²¹¹Rn_, _²²⁰Rn_, and _²²²Rn_ respectively.
The atomic number, which is 86 for radon, is usually not written because each element has a unique symbol that implicitly gives the atomic number; however, it is sometimes included for clarity, especially when dealing with transuranic elements or in educational contexts.

The atomic number of an element is a fundamental property that defines the element's identity. It is denoted by the letter 'Z' and represents the number of protons found in the nucleus of an atom.
Every atom of the same element has the same atomic number. For radon, the atomic number is 86, which means that every radon atom has 86 protons. Understanding atomic numbers helps us understand why elements behave the way they do chemically and why they are placed in specific locations on the periodic table.

Atoms of the same element can have different numbers of neutrons; these variations are called isotopes.

The Number of Neutrons:

To determine the number of neutrons in an isotope, you subtract the atomic number (number of protons) from the mass number. For example, the radon isotope with a mass number of 211 has 125 neutrons because 211 (mass number) - 86 (atomic number) = 125 (number of neutrons). The difference in neutron numbers leads to different mass numbers, which ultimately distinguishes one isotope from another.

The mass number, symbolized by 'A', is the total count of protons and neutrons in an atom's nucleus. It is a whole number because it counts particles.

Calculating the Mass Number:

To find the mass number, simply add the atomic number (Z) to the number of neutrons (N). For instance, if a radon atom has 125 neutrons, the mass number would be 86 (protons) + 125 (neutrons) = 211. Determining the mass number is crucial for understanding isotopes and for writing their notation, as seen in the examples for radon isotopes 211, 220, and 222.