Wave-particle duality is a fundamental concept in quantum mechanics stating that electrons, and all subatomic particles, exhibit both particle-like and wave-like properties.

As particles, electrons have mass, can collide with other particles, and occupy defined positions in space. This behavior is evident in experiments like the photoelectric effect, where electrons are ejected from metal surfaces when struck by light, confirming their particle nature.

As waves, electrons can exhibit interference and diffraction, behaviors typically associated with light or sound. This was famously demonstrated in the double-slit experiment, where electrons created an interference pattern when not observed—suggesting wave behavior.

This dual nature is described by quantum theory, especially through de Broglie’s hypothesis, which assigns a wavelength to particles based on their momentum.

Wave-particle duality is essential for understanding:

• The structure of atoms
• Electron orbitals and energy levels
• The basis of quantum mechanics, which governs how matter behaves at microscopic scales

It shows that classical ideas about particles and waves break down at the quantum level, requiring a new, probabilistic way of thinking about nature.