An electron is a negatively charged subatomic particle that orbits the nucleus of an atom. Electrons are fundamental particles, meaning they are not made of smaller components. They play a key role in electricity, chemical bonding, and atomic structure.
Properties of an Electron
✔ Charge: -1 (Negative)
✔ Mass: 9.109 × 10⁻³¹ kg (1/1836th the mass of a proton)
✔ Location: Outside the nucleus in the electron cloud
✔ Type: Lepton (a fundamental particle that does not interact via the strong nuclear force)
✔ Speed: Moves at near the speed of light within atoms
Role of Electrons in Atoms
✔ Determine Chemical Behavior – Electrons form chemical bonds and define how elements interact in reactions.
✔ Orbit in Energy Levels (Shells) – Electrons exist in discrete energy levels, moving between them by absorbing or releasing energy (quantum jumps).
✔ Balance the Atom’s Charge – The number of electrons equals the number of protons in a neutral atom.
Example:
- Hydrogen (H) has 1 proton and 1 electron.
- Oxygen (O) has 8 protons and 8 electrons.
Electron Configuration & Energy Levels
Electrons occupy energy shells around the nucleus, following a specific pattern:
- 1st shell: Holds up to 2 electrons
- 2nd shell: Holds up to 8 electrons
- 3rd shell: Holds up to 18 electrons
Example:
Carbon (C, atomic number 6) has an electron configuration of 2, 4 (2 in the first shell, 4 in the second).
Electrons and Chemical Bonding
✔ Ionic Bonds – Electrons are transferred between atoms (e.g., sodium donates an electron to chlorine in NaCl – table salt).
✔ Covalent Bonds – Electrons are shared between atoms (e.g., in water H₂O).
✔ Metallic Bonds – Electrons are delocalized, allowing metals to conduct electricity.
Electron vs. Other Subatomic Particles
| Property | Electron (e⁻) | Proton (p⁺) | Neutron (n⁰) |
|---|---|---|---|
| Charge | -1 (Negative) | +1 (Positive) | 0 (Neutral) |
| Mass | 1/1836th of a proton’s mass | 1.67 × 10⁻²⁷ kg | Slightly heavier than a proton |
| Location | Outside nucleus (electron cloud) | Inside nucleus | Inside nucleus |
| Function | Chemical bonding & electricity | Defines element (atomic number) | Stabilizes nucleus |
Where Do Electrons Come From?
✔ Big Bang & Early Universe: Electrons formed seconds after the Big Bang.
✔ Electricity & Current Flow: Moving electrons create electrical energy in circuits.
✔ Beta Decay: A neutron can transform into a proton and an electron (beta particle).
Uses of Electrons in Technology & Science
✔ Electricity & Circuits – Flowing electrons power everything from phones to cities.
✔ Electron Microscopes – Use electron beams for ultra-detailed imaging.
✔ Quantum Computing – Electrons play a role in next-gen computational technology.
✔ Cathode Ray Tubes (Old TVs & Monitors) – Use electron beams to create images.
Conclusion
Electrons are negatively charged fundamental particles that orbit the nucleus, enabling chemical reactions, electricity, and atomic interactions. Understanding electrons is key to physics, chemistry, and technology.