Paper 1 - Radioactive Decay Flashcards
What is the result of radioactive decay ?
When an unstable nucleus changes and emits particles, the atomic number can change. If this happens, the atom becomes a different element.
What happens during beta- decay ?
How does this affect the atomic number
A neutron in the nucleus of an unstable atom decays to become a proton and an electron. The proton stays within the nucleus, but the electron which Is the beta - particle, is emitted from the nucleus qy high speed as a fast moving electron.
N->p + e-
Mass number does not change but the proton number increases by 1
What happens during beta + decay ?
How does this affect the atomic number
A proton in the nucleus decays to become a neutron and a positron. The neutron stays in the nucleus. The positron -> which Is the B+ particle is emitted from the nucleus at a very high speed, carrying away a positive charge and a very small amount of the nuclear mass.
P-> n + e-
Mass number does not change but the proton number decreases by 1
How is the nuclei made more stable bu gamma ?
Nuclei may also lose energy as gamma radiation when subatomic particles in the nucleus are rearranged. This helps make them become more stable. Gamma no effect on either mass or charge of nucleus
Exam note - which decay has occurred
Students may be asked to complete each equation and state which decay has happened- change in mass / atomic number
What are the uses of beta decay
Carbon 14 unstable isotope of carbon and emits beta minus particles. Half life over 5700 years. -Can be used for radiocarbon dating, involves finding the ages of materials that are thousands of years old.
-positions can be used in hospitals to form images of patients by the use of PET scans.
What is a nuclear equation ?
A nuclear equation shows what happens during radioactive decay. The equation must be balanced - the total mass number must be the same on each sure question the total charges must be the same. Beta particles given a unit (+1, -1) to indicate charge . Atomic number for a nucleus or alpha particle also represents the amount of positive charge.
How do we ensure nuclei that have undergone radioactive decay keep a balanced equation ?
Nuclei that have undergone radioactive decay also undergo a rearrangement of their protons and neutrons . This involves the loss of energy from the nucleus in the form of gamma radiation - mass and charge of gamma must be zero for equation to balance
(WORKED EXAMPLE) alpha decay
238 92 uranium -> 234 90 thorium + 4 2 alpha particle + gamma ray.
Refer to periodic table to reference the element formed.
What happens in neutron decay ?
Neutron decay results in another isotope of the same element being formed. Mass number reduced by 1
(WORKED EXAMPLE) beta + decay
121 53 iodine -> 121 52 tellurium + 0 +1 beta particle.
(WORKED EXAMPLE) beta - decay
14 6 C -> 14 7 N + 0 -1 beta particle
