Quantum mechanics describes light and matter as having both wave-like and particle-like properties, known as wave-particle duality. According to quantum theory, light can exhibit wave-like behavior, such as interference and diffraction, as well as particle-like behavior, such as discrete packets of energy called photons. Similarly, matter, such as electrons and atoms, can exhibit both wave-like and particle-like properties.
The distinct lines in the emission spectra of elements, also known as atomic spectra, support the idea that light can behave as a particle. When an element is heated or excited, it emits light at specific wavelengths, resulting in a pattern of distinct lines in the spectrum. These lines correspond to specific energy levels of the atoms in the element. According to quantum mechanics, this discrete line spectrum is a result of the quantized energy levels of electrons in atoms. The emission of light as discrete lines supports the idea that energy is quantized and comes in discrete packets, or photons, which behave as particles. This phenomenon is known as the particle-like behavior of light, as it suggests that light is emitted and absorbed in discrete amounts, supporting the dual nature of light as both a wave and a particle