Matter as Waves and Particles. In 1923 French physicist Louis de Broglie suggested that all particles not just photons have both wave and particle properties. He calculated that every particle has a wavelength (represented by) equal to planck's constant (h) divided by the momentum (P) of particle = h/p. Electrons, atoms and all other particles have de Broglie wave lengths. The momentum of an object depends on its speed and mass