Chapter 2 Flashcards
What are the two opposing forces that maintain electrons in orbits around the nucleus?
electrostatic force and centrifugal force
Electrostatic force is the ___ between the negative electrons and positive protons.
attraction
Centrifugal force pulls the ___ away in order to keep the electrons from dropping into the nucleus.
electrons
What keeps the electrons in orbit around the nucleus?
the balance between electrostatic and centrifugal forces
T/F. Electrons close to the nucleus have a STRONG binding energy. Electrons far from the nucleus have a WEAK binding energy.
True.
T/F. The energy need to remove an electron from its orbit must not exceed the binding energy of the electron in the shell.
The energy need to remove an electron from its orbit must EXCEED the binding energy of the electron in the shell.
The emission and propagation of energy through space or a substance in the form of waves or particles.
radiation
The process by which certain unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state.
Radioactivity
The ___ shell is closest to the nucleus and has the ___ energy level.
K; highest
How is binding energy measured?
in kilo electron volts (keV)
In a tungsten atom, it takes ___ keV to remove a K-shell electron and ___ keV to remove a M-shell electron.
70; 3
An ___ is an electrically unbalanced atom. The production of ions is known as ___. An ion pair results when an electron is ___ from an atom.
ion; ionization; removed
T/F. Radiation is the same as radioactivity.
False, radiation is NOT the same as radioactivity
T/F. In dentistry, radioactivity is used not radiation.
False, radiation is used not radioactivity.
Tiny particles of matter that possess mass and travel in straight lines and at high speeds. Includes alpha particles, electrons, protons and neutrons.
particulate radiation
___ radiation is defined as the propagation of wavelike energy (without mass) through space or matter.
Electromagnetic
Electromagnetic radiations travel at what speed? And, in what form?
the speed of light
wave form
the distance from crest to crest
wavelength
the speed of wave
velocity
how many times a wavelength passes a given point.
frequency
A long wavelength has a ___ frequency. And a short wavelength has a ___ frequency.
low; high
Which has the shortest wavelength, radio or cosmic? Which has the lowest frequency?
shortest, highest - cosmic
longest, lowest - radio
T/F. X-rays are visible.
False
X-rays have no ___ or weight and have no charge. They travel at the speed of ___ and in ___ form. They travel in ___ lines that can be deflected or scattered.
mass; light; wave; straight
T/F. X-rays can be focused to a point.
False, they cannot. They always diverge from a point
X-rays can ___ liquids, solids and gases and are ___ by matter. They interact with materials and cause ____. They cause certain substances to ___ and can produce an ___ on photographic film. They cause ____ changes to living cells.
penetrate; absorbed; ionization; fluoresce; image; biological
What vacuum tube is the heart of the x-ray generating system that is several inches long and include a leaded-glass housing, negative cathode and positive anode?
x-ray tube
What part of the x-ray tube has a tungsten filament with a molybdenum cup?
cathode
What part of the x-ray tube has a tungsten target and a copper stem?
anode
What helps to cool the anode and filter the x-ray beam?
insulating oil
What prevents the oil from leaking out of the tubehead but still allows x-rays to pass through?
barrier material
the release of electrons from tungsten filament when electrical current passes through and heats filament
thermionic emission
T/F. The out shell electrons of tungsten atom acquire enough energy to move away from the filament and an ___ ___ forms around the filament. Electrons stay here until high voltage circuit is activated by pressing the ___ button.
electron cloud; exposure
When an electron that passes close to the nucleus of a tungsten atom is slowed down, an x-ray photon of lower energy known as ___ or ___ radiation results.
general; braking
General radiation accounts for ___% of x-ray energy.
70
An electron that dislodges an inner-shell electron from the tungsten atom results in the rearrangement of the remaining orbiting electrons and the production of an e-ray photon is known as ____ radiation.
characteristic - very small amount of x-rays produced
Penetrating x-ray beam that is produced at the target of the anode and that exits the tubehead.
primary radiation (primary beam or useful beam) most penetrating
x-radiation that is created when the primary beam interacts with matter (such as soft tissues of the head, the bones of the skull, and the teeth).
secondary radiation
less penetrating
a form of secondary radiation and is the result of x-ray that as been deflected from its path by the interaction with matter.
scatter radiation
detrimental to both the patient and radiographer
Is it possible for an x-ray photon to pass through matter or the tissues of a patient without any interaction?
yes, this is called no interaction
The total transfer of energy from the x-ray photon to the atoms of matter through which the x-ray beam passes.
absorption
When an x-ray photon collides with a loosely bound, outer shell electron and gives up part of its energy to eject the electron from its orbit. Ionization takes place
compton scatter
low-energy x-ray photon interacts with an outer-shell electron. No change in the atom occurs.
coherent scatter
