CH 6 Photons and X-ray Production

What are electromagnetic waves classified by?

wavelength/frequency

What is the particle model of electromagnetic waves?

electromagnetic waves are seen as a collection of particles called photons

How does the brightness of light relate to photons?

number of photons being emitted is correlated to brightness, more photons= brighter light

What determines the color of light?

wavelength

How does the energy of photons relate to wavelength?

Shorter wavelength=higher frequency and thus higher energy photons

What are electron orbitals?

specific energy levels around atom that electrons can occupy

What is the ground state of an electron?

lowest energy orbital (K shell, n = 1)

What do the K, L, and M shells correspond to in terms of principal quantum number?

K is n = 1, L is n= 2, M is n = 3.

How many electrons can the K shell hold?

2

How many electrons can the L shell hold?

8

What must to happen for an electron to move to a higher orbital?

it needs to gain energy

What has to happen for electron to move to a lower orbital?

lose energy

What is thermionic emission?

the process where a metal filament is heated to release electrons

What role does high voltage play in X-ray production?

high voltage accelerates ejected electrons towards the target material.

What is bremsstrahlung?

Xrays that are emitted when high-energy electrons slow down in the target material, losing KE. The lost KE is converted into photons.

What are characteristic X-rays?

X-rays that are emitted when electrons fill a vacancy in a lower orbital after one is knocked off.

How does the atomic number (Z) affect characteristic X-rays?

Higher Z means more electrons, so the energy difference between shells is higher thus producing higher energy photons

Why is tungsten commonly used as a target material for X-ray production?

Tungsten is used because it has a high atomic number and a high melting point.

What is the photoelectric effect?

when an incoming X-ray is completely absorbed by a bound electron, causing it to get ejected from atom

What factors influence the probability of the photoelectric effect?

energy of incoming X-ray photons, the atomic number (Z) of the material, and material's density.

What is Compton scattering?

when incoming X-ray photons are partially absorbed by an outer electron, causing the photon to scatter with less energy

What is attenuation in the context of X-rays?

reduction in the number of X-ray photons that penetrate a material due to interactions with atom

How does the photoelectric effect contribute to X-ray imaging?

it causes contrast in X-ray images bc materials with higher atomic numbers (like bones) attenuate X-rays more than softer tissues

What happens to the energy of an electron when it is accelerated by an electrical potential difference?

the difference in electrical potential energy is converted into KE, electron gains KE

What happens to the energy difference when electrons transition between orbitals?

The energy difference is emitted as photons

What is the relationship between the energy of emitted photons and the orbital energies of an atom?

when electron fills a vacancy, the difference in energy between the two orbitals is equal to the energy of the resulting photon