Wavelength is defined as the distance from peak to peak. Energy is inversely porportional to the wavelength. Visible light is one small part of the electromagnetic spectrum.
Light behaves both as a wave and a particle.
A pigment is any substance that absorbs light. The colour of the pigment comes from the wavelengths of light reflected. Chlorophyll is a complex molecule. If a pigment absorbs light energy, one of three things will occur. Energy is dissipated as heat.