Isotopes
Isotopes are atoms of the same element having the same atomic number but different mass numbers.
This means they have the same number of protons but different numbers of neutrons.
Isotopes have important uses in medicine, agriculture, archaeology, and nuclear energy, including relevance for Bihar’s cancer treatment and soil studies.
Basic Concept
- Atomic Number (Z) = Number of protons
- Mass Number (A) = Protons + Neutrons
- Isotopes: Same Z, different A
→ e.g.,- Hydrogen Isotopes:
- Protium (¹H) → 0 neutrons
- Deuterium (²H) → 1 neutron
- Tritium (³H) → 2 neutrons
- Hydrogen Isotopes:
📝 PYQ (BPSC): Which isotope of hydrogen has 2 neutrons? → Tritium
📝 Expected MCQ: Isotopes differ in...? → Number of neutrons
Characteristics of Isotopes
- Chemically similar (same electron configuration)
- Physically different (mass, density, radioactivity)
- Some are stable, others are radioactive
Common Isotopes and Uses
| Element | Isotopes (Example) | Application |
|---|---|---|
| Hydrogen | ¹H, ²H, ³H | Nuclear fusion, heavy water |
| Carbon | ¹²C, ¹³C, ¹⁴C | Carbon dating of fossils |
| Uranium | ²³⁵U, ²³⁸U | Nuclear fuel, bombs |
| Cobalt | ⁶⁰Co | Cancer radiotherapy (gamma source) |
| Iodine | ¹³¹I | Thyroid treatment |
| Phosphorus | ³²P | Agriculture: studying fertilizer use |
📝 PYQ (CDPO): Which isotope is used in cancer treatment? → Cobalt-60
📝 Expected MCQ: Which isotope is used for carbon dating? → Carbon-14
Bihar-Specific Relevance
🧬 Healthcare
- Cancer hospitals in Bihar (e.g., IGIMS, Patna) use Cobalt-60 for radiotherapy
- Iodine-131 used for thyroid treatments in medical colleges
🌾 Agriculture
- Phosphorus-32 used in soil and plant studies in RAU Pusa (Bihar Agricultural University)
- Helps understand fertilizer absorption efficiency
🧪 Archaeology
- Isotopic carbon dating (C-14) used to determine age of artifacts at sites like Nalanda, Vikramshila
Nuclear Isotopes & Energy
- Uranium-235 used in nuclear power (fission)
- India’s nuclear plants enriched with isotopes (not in Bihar, but nationally relevant)
- Isotopes help in radiotracer studies, industrial flaw detection
📝 Expected MCQ: Which isotope of uranium is used as fuel? → U-235
Differences: Isotopes vs Isobars
| Feature | Isotopes | Isobars |
|---|---|---|
| Atomic Number | Same | Different |
| Mass Number | Different | Same |
| Example | ¹H, ²H, ³H | ⁴⁰Ca and ⁴⁰Ar |
📝 Expected MCQ: Which pair are isobars? → Calcium-40 and Argon-40
PYQs + Expected MCQs
📝 PYQ (BPSC): Which hydrogen isotope is radioactive? → Tritium
📝 PYQ (CDPO): Use of isotopes in archaeology? → Carbon-14 dating
📝 Expected MCQ: Which isotope is used in thyroid disease? → Iodine-131
📝 Expected MCQ: Number of protons in isotopes of an element? → Same
📝 Expected MCQ: What changes among isotopes? → Neutron number
Quick Revision Points
- Isotopes = same atomic number, different mass number
- Chemically same, physically different
- Used in: medicine, archaeology, agriculture, nuclear power
- Bihar: Cobalt-60 (cancer), P-32 (fertilizer), C-14 (Nalanda finds)
- Radioactive isotopes = used in diagnosis and therapy
- Isobars = same mass, different atomic number
Sources Used
- NCERT Class 9–10 Science – Structure of Atom
- Lucent GK – Chemistry
- Drishti Quick Book – Science
- Ghatna Chakra & EduTeria BPSC PYQs
- RAU Pusa Agricultural Research Highlights
- IGIMS Patna – Nuclear Medicine Unit Reports