Structure
Matter is composed of atoms. An atom consists of a central nucleus surrounded by a cloud of electrons.
The nucleus is made up of A nucleons, including:
🔴 Z protons
Charge: +e ≃ 1.602 × 10-19 C
Mass: mp ≃ 938.272 MeV/c²
⚪ A − Z neutrons
No electric charge
Mass: mn ≃ 939.565 MeV/c²
🔵 Z electrons
Charge: −e
Mass: me ≃ 0.511 MeV/c²
Atoms interact with one another by sharing some of their electrons, leading to the formation of molecules.
Typical Dimensions
Characteristic distances and energies depend on the scale being considered.
📏 Subatomic dimensions
Nuclear size: 2–20 fm
Interatomic distances: 1–2.5 Å
⚡ Typical energies
Nucleon binding energies: 1–10 MeV
Molecular bonds: 1–10 eV
Intramolecular interactions: 1–100 meV
Wave–Particle Duality
In quantum mechanics, every particle exhibits both wave-like and particle-like properties.
As long as a particle is not observed1, its probability of being found behaves like a wave characterized by a wavelength λ [m].
⚫ During observation
When an observation is made, the particle exchanges energy with its surroundings and appears as a localized particle carrying all of its energy [eV].
1 A particle is observed by forcing it to exchange energy with its environment.