Question

The following isotopes have applications in medicine. Write their symbols in the form \({ }_{Z}^{A} X\). a. cobalt-60 b. phosphorus-32 c. iodine-131 d. sulfur-35

Short answer

\( {}_{27}^{60}Co \) for cobalt-60, \( {}_{15}^{32}P \) for phosphorus-32, \( {}_{53}^{131}I \) for iodine-131, \( {}_{16}^{35}S \) for sulfur-35.

Step-by-step solution

Identify the Atomic Number (Z)

To write the symbol of an isotope in the form \( {}_{Z}^{A}X \), identify the atomic number (Z), which is the number of protons in the nucleus of an atom of the element. You can find Z in the periodic table of elements.

Identify the Mass Number (A)

The mass number (A) represents the total number of protons and neutrons in an atomic nucleus. It is given in the name of the isotope (e.g., carbon-14 has a mass number of 14).

Write the Symbol for Cobalt-60

Cobalt's atomic number (Z) is 27. Since cobalt-60 indicates that the mass number (A) is 60, its symbol is \( {}_{27}^{60}Co \).

Write the Symbol for Phosphorus-32

Phosphorus's atomic number (Z) is 15. Given that phosphorus-32 has a mass number (A) of 32, its symbol is \( {}_{15}^{32}P \).

Write the Symbol for Iodine-131

Iodine's atomic number (Z) is 53. With iodine-131 having the mass number (A) of 131, the symbol is \( {}_{53}^{131}I \).

Write the Symbol for Sulfur-35

Sulfur's atomic number (Z) is 16. For sulfur-35 with a mass number (A) of 35, the symbol is \( {}_{16}^{35}S \).

Key concepts

Understanding Atomic Number

The atomic number, denoted by the symbol 'Z', is fundamental to identifying an element. It specifies the number of protons present in the nucleus of an atom. Unlike neutrons or electrons, the number of protons is fixed for a given element and defines its identity. For example, whether an atom is carbon, oxygen, or iron is determined solely by its atomic number: 6 for carbon, 8 for oxygen, and 26 for iron.

Every element's atomic number is unique and serves as its address within the periodic table. In isotope notation, the atomic number is usually placed as a subscript before the element symbol. Understanding the atomic number is vital for different areas of science, especially in medicine where isotopes are used for diagnosis and treatment. Those working in medical fields must comprehend how the atomic number relates to the element in use to ensure precise application.

Deciphering Mass Number

The mass number, represented by 'A', is the sum of protons and neutrons in the nucleus of an atom. It reflects the total number of these particles, which are collectively known as nucleons. Since electrons have negligible mass, they don't factor into the mass number. Importantly, isotopes of the same element have the same number of protons (atomic number) but differ in their number of neutrons, leading to different mass numbers.

In medicine, knowing the mass number of an isotope can dictate its behavior within the body. For example, isotopes with a higher mass number tend to be less stable and may be used for radiation therapy due to their tendency to decay, releasing particles that can destroy cancer cells. However, isotopes with a lower mass number might be preferred for imaging procedures as they emit less strong radiation, suitable for creating detailed body scans without damaging tissues.

Isotope Notation in Practice

Isotope notation is a compact way to provide detailed information about an atom's identity and composition. It includes the element's symbol along with its atomic number and mass number. The standard form is \( {}_{Z}^{A}X \), with 'X' representing the chemical symbol of the element, 'Z' as the atomic number, and 'A' as the mass number. Isotope notation is particularly useful when dealing with different isotopes in medicine. It allows healthcare professionals to quickly identify the specific isotope and understand its properties.

For instance, Cobalt-60 (\( {}_{27}^{60}Co \) in isotope notation) is used for cancer treatment, while Iodine-131 (\( {}_{53}^{131}I \) in isotope notation) is significant for diagnosing and treating thyroid disorders. The clear representation of isotopes helps maintain accuracy and safety in medical procedures.