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đź’ˇ The neutral one
In 1932 James Chadwick found the missing piece — a particle with the mass of a proton but no charge at all.
What is a neutron?
Neutron
A neutral particle in the nucleus (no charge) with mass nearly equal to that of a proton. Found in all atoms except hydrogen; symbol n
- A subatomic particle with no electric charge (neutral).
- Its mass is nearly equal to that of a proton.
- Found in the nucleus of all atoms except hydrogen ; symbol n .
| S.No. | Subatomic particle | Symbol | Relative charge |
|---|---|---|---|
| 1 | Electron | e − | −1 |
| 2 | Proton | p + | +1 |
| 3 | Neutron | n 0 | 0 |
🧵 Threads of Curiosity
- Lighter atoms often have equal protons and neutrons.
- Carbon has 6 each; oxygen has 8 each.
- Heavier atoms need more neutrons than protons.
- Iron: 26 protons, 30 neutrons. Uranium: 92 protons, 146 neutrons.
- All protons are positive, so they repel one another.
- Neutrons space the protons apart and reduce this repulsion.
- They also strengthen the nuclear force binding the nucleus.
🔬 Ready to Go Beyond
- The neutron opened a new era in atomic physics.
- Being uncharged, neutrons enter nuclei very easily.
- This led to artificial radioactive elements.
- It also led to the splitting of uranium atoms.
- This gave birth to the ‘atomic age’.
- It allowed both nuclear power and nuclear weapons.
👤 Meet a Scientist — James Chadwick
- Worked under Rutherford at the Cavendish Laboratory, Cambridge.
- Discovered the neutron in 1932 , explaining atomic mass.
- Won the Nobel Prize in Physics (1935) .
🌎 India’s Scientific Contributions
The Bhabha Atomic Research Centre (BARC) , Mumbai, leads advanced neutron-scattering experiments using reactors such as Dhruva . This reveals insights into superconductors, battery electrodes and drug molecules — helping develop better medicines, energy storage and industrial alloys in India.
âś… Test Yourself
-
Who discovered the neutron, and when?
Show Answer
James Chadwick, in 1932. -
What is the charge on a neutron?
Show Answer
Zero — it is electrically neutral. -
Which atom has no neutron in its nucleus?
Show Answer
Hydrogen. -
What force binds protons and neutrons together?
Show Answer
The nuclear force .
Important Definitions
- Neutron — a neutral subatomic particle (no charge) in the nucleus, with mass nearly equal to a proton.
- Nuclear force — the strong force that binds protons and neutrons together in the nucleus.
The Three Subatomic Particles
| Particle | Symbol | Relative charge | Location |
|---|---|---|---|
| Electron | e − | −1 | Outside the nucleus (in shells) |
| Proton | p + | +1 | Inside the nucleus |
| Neutron | n 0 | 0 | Inside the nucleus |
