Exambusters Study Cards 19 Radioactivity

Beta Particle

*an electron ejected from the nucleus when a neutron decays to a proton

*increases atomic number by one

*high velocity

*low energy

Alpha Particle

*a helium nucleus

*charge = 2+

*high energy

*low velocity

*ejection reduces atomic number by 2 amu and atomic weight by 4 amu

Gamma Radiation

*usually emitted with beta radiation

*has neither charge nor mass

*high energy

*part of the electromagnetic spectrum; travels at the speed of light

Compare a chemical reaction to a radioactive reaction

In a chemical reaction the elements’ bonds are broken and new molecules are formed.

In a radioactive reaction, new elements are formed; nuclei are changed.

Binding Energy
The net energy required to decompose a molecule, atom, or nucleus into its constituent particles.
Write the nuclear equation: U238 loses an alpha particle
92U238;; 90Th234 + 2He4
Write the nuclear equation: Th234 ejects a beta particle
90Th234;; 91Pa234 + -1e0
Chain Reaction
A reaction produced during nuclear fission when at least one neutron from each fission produces another fission. The reaction is self-sustaining. This process takes place when a bomb is detonated.
Half-Life
The time it takes for half of a radioactive sample to decay. Can range from a fraction of a second to years. “Carbon dating” is commonly used to determine the age of fossils by measuring the proportion of the radioactive isotope C-14 in a sample.
Transmutation
The conversion oa an element to a new element due to a change in number of protons. e.g. alpha or beta decay
Fission
The breakdown of heavy nuclei into lighter nuclei. Source of “nuclear power.”
Fusion
The joining of lighter nuclei to form heavier nuclei. Source of the sun’s energy.