To understand the derivation of the Compton scattering formula. In 1923, Arthur H. Compton conducted a series of experiments that demonstrated the particle-like nature of electromagnetic radiation. Compton studied the collision of photons from a uniform wavelength beam with a stationary target. He observed that the radiation that exited from the target showed two characteristic wavelengths, one at the original wavelength λ and another at a new wavelength λ′ shifted by an amount Δλ from the original.
In this problem we will use the principles of conservation of energy and conservation of momentum, coupled with some basic ideas in quantum physics and relativity, to derive a statement for the shifted wavelength λ′.
1. Consider a photon with initial momentum pi on a collision course with a stationary electron of mass m. What is the total energy Ei of these two particles before the collision?
Don't forget to include the rest mass energy of the electron. Express your answer in terms of the pi, the speed of light c, and m.

Up of elements with the same number of valence electrons. vertical column in the periodic table of elements such as alkali metals or halogens. a horizontal row of elements in the periodic table. this is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table. periodic trend these are the highly reactive elements located in group 1 of the periodic table. these elements have one electron in their outer energy level which makes them highly reactive with water and halogens. these are the reactive elements located in group 2 of the periodic table. these elements have two electrons in their outer energy level which makes them reactive with water and halogens. alkaline earth metals these are the group 3 or d-block elements. these dense metals with high boiling points can have different oxidation states and all are solid at room temperature with the exception of mercury. transition metals this is the highly reactive family of elements with 7 valence electrons. this is an element with full valence shell, very unreactive. this is a group of elements with few valence electrons that conducts heat and electricity. one of a class of elements having properties intermediate to metals and nonmetals. this is a type of element that has many valence electrons, not a conductor.