BharatNotes Isotope
nounUsage in a UPSC answer
India's civil nuclear programme and its push for radioactive isotopes in medicine and agriculture illustrate how mastery of fissile and non-fissile isotopes has become integral to both energy security and public health.
Synonyms
Word Family
isotopic (adj), isotopically (adv), radioisotope (n), isotopy (n)
Root
Greek isos = equal; topos = place — same place on the periodic table; coined by M. Todd, 1913
Etymology
From Greek isos ("equal") + topos ("place"), meaning "the same place" on the periodic table; coined by Scottish physician Margaret Todd in 1913.
Memory Hook
ISO (same) + TOPE (think "topos" = place): isotopes are atoms of the same element sitting in the SAME PLACE on the periodic table, just carrying different neutron "luggage".
How This Word Works in UPSC Writing
Atoms of the same element having the same number of protons but different numbers of neutrons, so they share atomic number and differ in mass number. The consequence that structures the whole topic is that chemical behaviour is set by electrons and therefore by proton count, so isotopes of an element are chemically near-identical while differing physically and, where unstable, in radioactivity. This is what makes them useful as tracers, since a labelled compound behaves chemically like the unlabelled one but can be followed. It also explains why atomic masses on the periodic table are rarely whole numbers, chlorine's 35.5 being the weighted average of its isotopes rather than the mass of any actual atom. Applications worth naming are carbon-14 in dating, cobalt-60 in radiotherapy and food irradiation, iodine-131 in thyroid treatment, and uranium-235 as the fissile isotope against fertile uranium-238 and thorium-232, which India's three-stage programme converts to fissile uranium-233.
Don’t Confuse It With
Isotopes share the atomic number and differ in mass number, so they are the same element. Isobars share the mass number and differ in atomic number, so they are different elements. Isotones share the neutron number. A radioisotope is simply an isotope that is unstable and decays, so not all isotopes are radioactive. Fissile material sustains a chain reaction directly, while fertile material such as thorium-232 must first absorb a neutron and transmute into a fissile isotope.
Hindi Meaning
समस्थानिक (samasthānik); समभारिक is isobar and समन्यूट्रॉनिक is isotone.
Common Questions
- What is an isotope?
- An atom of the same element having the same number of protons but a different number of neutrons, giving the same atomic number and a different mass number.
- What is the difference between isotopes and isobars?
- Isotopes are atoms of the same element with different mass numbers, while isobars are atoms of different elements that happen to share the same mass number.
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