Ch. 38 RHS From the book

_____ are the basic form of matter, and they contain energy

Atoms

______ is anything that occupies space and has form or shape.

Matter

Matter is composed of atoms grouped together in specific arrangements called _________

molecules

A ________ is the smallest particle of substance that retains the property of the original substance.

molecule

The atom consists of two parts: ___________

a central nucleus and orbiting electrons

Electrons remain ______ in their orbit unless disturbed or moved

stable

Dental x-rays _______ (do or do not?) affect the tightly bound nucleus of atoms

do not

X-rays can be what? X-rays can affect what part of the atom and how?

scattered (change direction) and can knock electrons out of their orbits.

ionization? what happens?

X-rays can be scattered (change direction) or can knock electrons out of their orbits.

Dental x-rays _______ (can or cannot?) make atoms radioactive.

Answer- cannot. Explanation- Patients do not give off x-rays after the x-ray machine stops producing x-rays.

What are electrons ?

are tiny, negatively charged particles that have very little mass.

Electrons are maintained in orbit by ________, a force similar to gravity

electron binding energy

How is electron binding energy created

Binding energy is created by the attraction of the negatively charged orbital electrons to the positively charged protons contained in the nucleus.

Bremsstrahlung radiation is what kind of radiation

is the primary kind of radiation

Bremsstrahlung radiation is produced where?

produced in the dental x-ray tubehead

How is Bremsstrahlung radiation produced? describe the process

when an electron from the cathode directly hits the nucleus of a target atom, causing it to stop suddenly, or passes so close to the nucleus of a target atom that the negatively charged (–) electron is pulled off course by the positively charged (+) nucleus, slowing it down considerably.

Bremsstrahlung is radiation that is produced when high-speed electrons are ______________.

suddenly slowed down or deflected.

Bremsstrahlung radiation information card- No questions or answers just info

• Electron from the cathode:

  • In an x-ray machine, electrons are released from the cathode (a negatively charged electrode).

  • These electrons travel at high speed toward the anode (positively charged target, usually made of tungsten).

• Two main interactions are described:

  A. Direct Hit on the Nucleus:

  • If the high-speed electron hits the nucleus of a target atom directly, it stops suddenly.

  • This sudden stop causes the electron to release energy in the form of x-rays (Bremsstrahlung radiation).

  B. Passing Close to the Nucleus:

  • If the electron doesn't hit the nucleus but passes very close to it, the positive charge of the nucleus attracts the negative electron.

  • This pulls the electron off course and slows it down.

  • The lost energy from this sudden deceleration is also released as Bremsstrahlung x-rays.

Electrons remain stable in their orbit around the nucleus until ______________.

radiograph photons collide with them.

Ions are atoms that gain or lose an ______ and become electrically unbalanced

electron

X-rays belong to a group classified as _________ radiation

electromagnetic

The use of 85 to 100 kV produces ___ (more/less) penetrating dental x-rays with _____(more/less) energy and shorter wavelengths.

more;more

what is Photoelectric effect

This is a form of absorption of the x-ray photon that occurs when the photon collides with an inner shell electron, causing ejection of the electron from its orbit. The photon ceases to exist because all its energy is given up during the collision. This occurs in about 30% of interactions with matter.

what is Compton scatter

Most interactions (62%) are of this type of scatter in which the incoming photon hits and knocks an outer shell electron from orbit, giving up a portion of its energy.

what is coherent scatter

this is a type of scatter in which an x-ray photon collides with an outer shell electron and scatters off in another direction without a loss of energy. This happens in about 8% of interactions.