Atoms and Light Flashcards

Question

What are the properties of electromagnetic radiation?

Answer 1

1. Don't need a medium to travel through 2. Move at speed of light 3. Wave like properties e.g. interfere, reflect, refract and diffract

Answer 2

Electric field

Answer 3

Magnetic field

Answer 4

1. Black body radiation | 2. Photoelectric effect and compton effect

Answer 5

“black body”, an object that absorbs all electromagnetic radiation that falls upon it – none passes through and none is reflected. Since no light is reflected or transmitted, the object appears black when it is cold. However, above absolute zero, a black body emits thermal radiation with a spectrum that depends on temperature

Answer 6

When a metallic surface is exposed to electromagnetic radiation, above a certain threshold frequency, the light is absorbed and electrons are emitted (see figure, right). In 1902, Philipp Eduard Anton von Lenard observed that the energy of individual emitted electrons increases with the frequency of the light. This was at odds with Maxwell’s wave theory of light, which predicted that the electron energy would be proportional to the intensity of the radiation. In 1905, Einstein resolved this paradox by describing light as composed of discrete quanta (photons), rather than continuous waves.

Answer 7

In 1923, Compton investigated the scattering of high energy X-rays and &-ray from electrons in a carbon target. By measuring the spectrum of radiation at different angles relative to the incident beam, he found two scattering peaks. The first peak occurred at a wavelength which matched that of the incident beam, while the second varied with angle. Within the framework of a purely classical theory of the scattering of electromagnetic radiation from a charged particle – Thomson scattering – the wavelength of a low-intensity beam should remain unchanged. Compton’s observation demonstrated that light cannot be explained purely as a classical wave phenomenon. Light must behave as if it consists of particles in order to explain the low-intensity Compton scattering. If one assumes that the radiation is comprised of photons that have a well defined momentum the shift in wavelength can be understood

Answer 8

Particles with discrete amount of energy and . momentum

Answer 9

Frequency and wavelength of EM radiation via planck's constant

Answer 10

Either waves or particles

Answer 11

Energy of atoms and sub-atomic particles

Answer 12

electron Volt (eV)

Answer 13

The amount of energy gained by an electron as it is accelerated through a potential difference of 1V

Answer 14

Wavelength

Answer 15

Wavelength

Answer 16

delta E = E2-E1 between electrons in 2 orbitals

Answer 17

If the electron drops from higher energy state in orbital 2 to lower energy state in orbital 1 Energy is emitted as a photon of EM radiation

Answer 18

Energy difference of orbitals

Answer 19

If an incoming photon has an energy equal to the difference in energy between the two orbitals then it will be absorbed and the electron will be excited from orbital 1 to orbital 2

Answer 20

elements such as molybdenum when electrons move between energy levels

Answer 21

High energy electrons from the cathode strike the molybdenum target They knock out electrons from the lower energy levels leaving a vacancy Electrons in the higher energy orbitals fall down to fill the gap and emit photons of EM radiation in the x-ray range