radioactivity Flashcards by Alyssa Lizelle Uy

Protons and neutrons are packed tightly in the ______, where you find most of the atom’s mass.

Nucleus

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Since protons repel each other, the ________ allows protons and neutrons to be attracted to each other

strong nuclear force

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4x stronger than electric force

strong nuclear force

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protons and neutrons in the atomic nucleus co-exist in a state of
peaceful tranquility

stable isotopes

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Isotopes which spontaneously emit radiation are called

“radio-isotopes”

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the process in which an unstable atomic
nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves

radioactive decay

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In 1896, he discovered, almost by accident, that uranium can blacken a photographic plate, even in the dark

Henri Becquerel

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the Father of Radioactivity

HENRI BECQUEREL

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Henri Becquerel shared the Nobel Prize in Physics with _____
and ____ _______ “in recognition of the extraordinary services he has rendered by his discovery of spontaneous
radioactivity”

Pierre and Marie Curie

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Radioactive materials such as Uranium was first discovered by Henri Becquerel and was studied extensively by

MARIE AND PIERRE CURIE

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Marie and Pierre Curie discovered other natural radioactive elements such as

Radium and Polonium

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From before the creation of the Earth

primordial

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Formed as a result of cosmic ray interactions

cosmogenic

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Enhanced or formed due to human actions (minor
amounts compared to natural)

human produced

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Radon from the decay of Uranium and Thorium
Potassium-40 - found in minerals and in plants
Carbon 14 - found in plants and animal tissue

Naturally Occurring Sources

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◆ Medical use of Radioactive Isotopes
◆ Certain consumer products - e.g. smoke detectors
◆ Fallout from nuclear testing
◆ Emissions from Nuclear Power

manmade sources

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types of radioactivity

natural and artificial

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◆ By existence, there are elements here on Earth that are
radioactive
◆ Found in nature
● Uranium, Thorium, Radium

Natural radioactivity

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◆ The first major advance occurred in 1930’s with the
invention of the cyclotron by Ernest Lawrence in
Berkeley, California
◆ Enrico Fermi in Rome started systematically exposing
the elements in the Periodic Table to bems of neutrons
● He identified around 40 new radioactive species
and thus was able to show how neutrons that was able to show how neutrons that had been slowed
down prior to interacting with the targets gave
rise to much higher levels of radioactivity

Artificial Radioactivity

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first major advance occurred in (year) with the
invention of the cyclotron by _______ in
Berkeley, California

Ernest Lawrence 1930

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in rome, he started systematically exposing
the elements in the Periodic Table to beams of neutrons. He identified around 40 new radioactive species and thus was able to show how neutrons that was able to show how neutrons that had been slowed down prior to interacting with the targets gave rise to much higher levels of radioactivity

Enrico Fermi

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Is the energy that is released as particles or rays,
during radioactive decay

radiation

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Is the property of an atom that describes spontaneous changes in its nucleus that create a different element

radioactivity

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The rate of emission is referred to as a material’s ______

activity

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each occurrence of a nucleus throwing off particles or energy is referred to as

disintegration

The number of disintegrations per unit time (minutes, seconds, or hours) is called the

activity of a sample

Activity is expressed in

curies

One curie equals

37 billion dps

Produced during World War II in Berlin

DORAMAD RADIOACTIVE TOOTHPASTE

In the U.S, hundreds of thousands of people began drinking bottled water laced with radium, as a general elixir known popularly as

liquid sunshine

It was a little strange, Fryer said that when she blew her nose, her handkerchief glowed in the dark. But everyone knew that the paint was harmless. The women even painted their nails and their teeth to surprise their boyfriends when the lights went out

radium dials

the rate of decay is also known as

half-life

the time required for the disintegration of one-half of the radioactive atoms that are present when measurement starts ■ It does not represent a fixed number of atoms thatdisintegrate, but a fraction

half-life (t1/2)

types of half-life

physical, biological, effective

The time it takes for a radioactive atom to half its original activity by 50%

physical half life

Is the time an organism takes to eliminate one half the amount of a compound or chemical on a strictly biological basis

biological half-life

Incorporates both the radioactive and biological half-lives

EFFECTIVE HALF-LIFE

It is used when health physicists calculate the dose received from an internal radiation source

EFFECTIVE HALF-LIFE

tells how quickly the radioactivity from the radionuclide will decrease

half life

The number of _____ tells how active it is now

curies

The series of transformations that a given radionuclide will undergo, as well as the kind of radiation it throws off, are characteristic of the radionuclide

decay chain

important for planning for the management and disposal of radioactive materials and waste and for site cleanup

radionuclide decay chains

the increasing concentration of decay products and activity is called

ingrowth

________ for a decay chain occurs when each radionuclide decays at the same rate it is produced

radioactive equilibrium

when the production and decay rates of each radionuclide in the decay chain are equal, the chain has reached

radioactive equilibrium

the original radionuclide and decay product half-lives are similar

TRANSIENT EQUILIBRIUM

the original radionuclide has a much longer half-life

secular equilibrium

the decay product has a longer half-life

no equilibrium

● stable nuclides of the lighter elements have approximately equal numbers of protons and neutrons ● however, as Z increases the ‘stability line’ curves upwards ● heavier nuclei need more and more neutrons to be stable

stability

heavier nuclei need more and more _______ to be stable

neutrons

- a radio-nuclide above the stability line decays by B-emission ● because it loses a neutron and gains a proton, it moves diagonally towards the stability line

beta decay

Is a subatomic particle, which resides in the nucleus of an atom

neutron

do not have charge. Its mass is 1.674927 X 10^-27 kg, which is slightly higher than the mass of a proton

neutrons

the neutrino was postulated first by_______ in 1930 to explain how beta decay could conserve energy

Wolfgang Pauli

is a subatomic particle with a small mass (similar to electrons) and no electrical charge. Since there is no electrical charge, ______ are not affected by the electrical or magnetic forces. It is shown by the letter v(nu)

neutrino

discovered a much more massive nuclear particle in 1932 and also named it a “neutron”

James chadwick

who developed the theory of beta decay, coined the term “neutrino”

enrico fermi

is the Italian equivalent of “little neutral one”

NEUTRINO

is an antimatter particle, the counterpart to the neutrino

antineutrino

occurs when the nucleus is too large

ALPHA PARTICLE EMISSION

when the ratio of neutrons to protons in the nucleus is too low, certain atoms restore the balance by emitting

alpha particles

it occurs when the neutron to proton ratio is too great in the nucleus and causes instability

beta decay

many radioactive nuclides decay by

B-emission

represented by B+

positron decay

particle with same mass as an electron but with a positive charge (antimatter version of an electron)

positron

an electron from the closest energy level falls into the nucleus, which causes a proton to become a neutron

ELECTRON CAPTURE

a process where a nucleus with excess energy can get rid of that energy without altering its proton or neutron count

internal conversion

the excess energy of the nucleus is transmitted to the orbital electron of an atom, which is subsequently ejected from the atom

internal conversion

x-rays are emitted as the atom attempts to restore its neutrality

INTERNAL CONVERSION

sometimes a nucleus that is still unstable after a beta or alpha decay is still unstable so may emit ______ to become more stable

gamma radiation

occurs because the nucleus is at too high an energy

gamma decay

rather than emitting another beta or alpha particle, this energy is lost by emitting a pulse of electromagnetic radiation called

gamma rays

nuclear process in which a nucleus with excess energy following the emission of an alpha particle or a beta particle emits energy without changing its number of protons or neutrons

isomeric transition