Transcript Types of Radiation in the Electromagnetic Spectrum Office 2003

 Personal Radiation Dose
 IONIZING AND NON-IONIZING RADIATION
 Non-ionizing:
 Carries LESS energy
 Can only excite the water molecule.
 Ionizing:
 Carries MORE energy than 1216 kJ/mol
 Can remove an electron from a water molecule
 Strips an electron from a molecule
 Molecule becomes positively charged.
 Can cause the formation of free radicals
 Contain an unpaired valence-shell electron and are
extremely reactive.
 Destroy biologically active molecules
 Either remove electrons or removing hydrogen atoms from
them.
 Damage the membrane, nucleus, chromosomes, or
mitochondria of the cell;
 this inhibits cell division
 results in cell death
 produces a malignant cell.
 Alpha
 Nuclei of Helium
 Charge = +2
 Stopped by a piece of paper
 Beta
 Beta- (electron emission)
 Beta + (positron emission or electron capture)
 Positron
 They cause most damage when they are emitted inside
the human body.
 Less ionizing
 Damage includes burns and cancer through mutations
 Dangerous in direct exposure (degree of danger is a
subject of debate)
 Animals (including humans) can also be exposed to
ionizing radiation internally
 if radioactive isotopes are present in the environment,
they may be taken into the body.
 Example:
 radioactive iodine is treated as normal iodine by the body
and used by the thyroid
 its accumulation there often leads to thyroid cancer.
Principal Effect of low doses: to induce
cancers which don’t manifest for 20
years
Principal Effect of high doses:
 More immediate effects
 Cells that are actively dividing are
more susceptible to radiation
exposure
 Bone marrow & skin more likely to
sustain injury than the central
nervous system or the kidneys.
 Has enough energy to make the
atoms in a molecule vibrate, but
not remove electrons
 Large ranges:
 UV, visible light, infrared,
microwaves, radio waves, and
other low frequency waves.
 Thought to be essentially
harmless below the frequencies
that cause heating.
 At low-energy end of the electromagnetic spectrum: (radio
waves and microwaves)
 Excites the movement of atoms and molecules, which is
equivalent to heating the sample.
 In or near the visible portion of the spectrum:
 Excites electrons into higher-energy orbitals.
 When the electron eventually falls back to a lower-energy
state, excess energy is given off to neighboring molecules in
the form of heat.
Principal effect of non-ionizing radiation =
increase in the temperature of the system.
 Non-Ionizing: 7 moles of photons of visible light
 Ionizing:
 300 joules of x-ray or gamma-ray radiation lethal
 Even though it only raises the temperature of the body
0.001°C!
 Internally, alpha particle radiation is even more
dangerous; a dose equivalent to only 15 joules is fatal for
the average human;
 7 x 10-10 moles of the particles emitted by alpha particles of
238U
is fatal.
 Polonium-210 (alpha emitter) suspected in lung, bladder
cancer related to tobacco smoking!
 Kill cancerous cells
 Generate electricity
 Problem: waste produces ionizing radiation
 Radiography—enhancing images that are hard to
capture, such as inside the body.
 Irradiating food
 Medical sterilization
 Sterile insect technique