Some animals, like snakes, have infrared detectors that enable them to locate their prey-typically small, warm-blooded, infrared-light-emitting mammals. Your body emits infrared radiation that can be detected by some cameras. Consider your own body, which typically has a temperature of approximately 98.6 ✯ or 36 ✬. In these studies, an object heated to a particular temperature emits radiation. The first arose during investigations by the German physicist Max Planck (1858–1947) of what is known as black body radiation. Two types of experiments in particular gave results that did not appear to be compatible with the wave theory. In the case of electromagnetic waves, λν = c, where c is the velocity of light.Īlthough the wave theory explained many of the properties of light, it did not explain them all. For all waves, the frequency times its wavelength equals the velocity of the wave. A light wave can be described by defining its frequency (ν) and its wavelength (λ). James Clerk Maxwell (1831–1879) developed the electromagnetic theory of light, in which visible light and other forms of radiation, such as microwaves, radio waves, X-rays, and gamma rays, were viewed in terms of perpendicular electric and magnetic fields. There was compelling evidence to support both points of view, which seemed to be mutually exclusive, and the attempt to reconcile these observations into a single model proved difficult.īy the end of the 1800s, most scientists had come to accept a wave model for light because it better explained behaviors such as interference and diffraction, the phenomena that gives rise to patterns when waves pass through or around objects that are of similar size to the wave itself. Historically, there had been a long controversy about the nature of light, with one side arguing that light is a type of wave, like sound or water waves, traveling through a medium like air or the surface of water and the other side taking the position that light is composed of particles. While Rutherford and his colleagues worked on the nature of atoms, other scientists were making significant progress in understanding the nature of electromagnetic radiation, that is, light.

To complete this picture leads us into the weird world of quantum mechanics. So many questions and so few answers! Clearly Rutherford’s model was missing something important and assumed something that cannot be true with regard to forces within the nucleus, the orbital properties of electrons, and the attractions between electrons and protons. But, as we know, most atoms are generally quite stable. As the electron orbits the nucleus this loss of energy will lead it to spiral into the nucleus – such an atom would not be stable. Maxwell – see below) a charged object emits radiation when accelerating. If you know your physics, you will recognize that (as established by J.C. What enables them to stay so close to each other? On the other hand, if electrons are orbiting the nucleus like planets around the Sun, why don’t they repel each other, leading to quite complex and presumably unstable orbits? Why aren’t they ejected spontaneously and why doesn’t the electrostatic attraction between the positively-charged nucleus and the negatively-charged electrons result in the negatively-charged electrons falling into the positively charged nucleus? Assuming that the electrons are moving around the nucleus, they are constantly accelerating (changing direction). For example because like charges repel and unlike charges attract, it was not at all clear why the multiple protons in the nuclei of elements heavier than hydrogen did not repel each other and cause the nuclei to fragment. Even as he articulated his planetary model of the atom, Rutherford was aware that there were serious problems with it.

Atomic orbitals explained