Isotope

🔹 What is an Isotope?

An isotope is a version of a chemical element that has:

• The same number of protons (same atomic number)

• But a different number of neutrons,

• Which means a different atomic mass (mass number)

👉 In short:

Isotopes = same element (same protons), different neutrons → different mass

🔹 Example:

Carbon (C) has 3 main isotopes:

➡️ All are carbon atoms (6 protons), but their neutron count and masses differ.

🔹 Types of Isotopes:

1. Stable Isotopes

   • Do not decay over time.

   • Examples: ¹²C, ¹⁶O, ²H (deuterium)

2. Radioactive Isotopes (Radioisotopes)

   • Are unstable, and decay over time by emitting radiation.

   • Examples: ¹⁴C, ¹³¹I, ²³⁸U

🔹 Uses of Isotopes:

🧬 In Medicine

• Diagnosis and treatment of diseases using radioactive isotopes.

• Examples:

  • Iodine-131 for thyroid treatment

  • Technetium-99m for imaging bones, heart, liver, etc.

🕰 In Archaeology

• Carbon-14 dating is used to determine the age of ancient organic materials (up to ~50,000 years old).

⚛ In Energy

• Isotopes like Uranium-235 and Plutonium-239 are used as nuclear fuel in power plants.

🔬 In Research

• Labeled isotopes help trace chemical and biological pathways in experiments.

🔹 How Isotopes Are Written

Isotopes are written in two ways:

1. Name format:

   • Carbon-14, Uranium-238, Iodine-131

2. Nuclear notation:

   ZAX^A_Z\text{X}

   • X = element symbol

   • Z = number of protons (atomic number)

   • A = number of protons + neutrons (mass number)

   Example:
   614C^ {14}_6 C = Carbon-14

🔹 Summary Table

✅ Key Takeaways:

• Isotopes are variants of the same element with different masses.

• They behave chemically the same, but nuclearly different.

• Some are stable, others radioactive.

• Widely used in science, energy, medicine, and archaeology.