Final answer:
Louis de Broglie theorized that electrons have wave principles, which was confirmed experimentally by C. J. Davisson and L. H. Germer's interference patterns. This led to the understanding of wave-particle duality in quantum mechanics.
Step-by-step explanation:
The concept that electrons exhibit wave principles was introduced by French physicist Louis de Broglie. In his 1925 PhD thesis, de Broglie proposed that just as light has wave-particle duality, electrons and other subatomic particles like protons also show wavelike behavior. His theory implied that any particle with momentum can be described by a wave equation, which was a groundbreaking idea leading to the development of quantum mechanics.
De Broglie's hypothesis was experimentally confirmed by C. J. Davisson and L. H. Germer, who observed an interference pattern with electrons, akin to wave characteristics. This wave-particle duality of electrons suggests that under certain experimental conditions, electrons can exhibit wave properties, while in others, they display characteristics of localized particles. Later, physicist Erwin Schrödinger developed wave mechanics to mathematically describe the motion of electrons, taking into account their wavelike behavior.