Chp 3: Nuclear Reactions Flashcards
Describe the nuclear model of the atom
The atom is made up of a nucleus consisting of positively charged protons and neutral neutrons (nucleons). This nucleus is then surrounded by much light, negatively charged electrons.
These 3 are called subatomic particles.
Why do protons repel eachother?
Like charges repel therefore, two protons will also tend to repel each other because they both have a positive charge.
Define the strong nuclear force
The SNF attracts protons and neutrons to each other as it is an attractive force that acts upon very tight nucleons.
How do you know if a nuclide is stable?
- doesn’t gain/lose any subatomic particles over time
- the coulomb force is balanced by the SNF (relative repulsions v attraction)
- If there are equal protons to neutrons
Define natural radioactive decay
The atom of a nucleus will naturally emit particles and or energy. The removal of energy allows for the nucleus to become more stable
Define/describe alpha radiation
Alpha decay is essentially adding a helium atom into a decay equation. ‘α’ has 2 protons and 2 neutrons and has the lowest penetrating ability. It travels a few centimeters and is highly ironizing.
Define/describe beta positive radiation
Beta positive decay is changing a neutron to a proton (hence the positive). The atomic number changes (bottom number) by one. β+ releases a neutrino also during decay. Moderate penetration and ironizing abilities.
Define/describe beta negative radiation
Beta negative decay is changing a proton to a neutron (hence the negative). The atomic number changes (bottom number) by one. β− releases a antineutrino also during decay. Moderate penetration and ironizing abilities.
Define/describe gamma radiation
Gamma decay occurs when an energetic, radioactive nucleus emits a gamma ray ɣ. There is NO change in atomic mass or number. It has no charge but is highly penetrable and can travel up to a few kilometers. This is what makes it so dangerous to living things.
What’s the difference between a parent and daughter nucleus
A daughter nucleus is the isotope that undergoes radioactive decay in order to form a parent nucleus
How does an excess in particles cause decay?
A daughter nulceus has an excess in particles causing it to become radioactive. This is why it undergoes either alpha or beta decay, to stabilize the atom.
Define a decay series
Sequence of decays the a daughter nucleus undergoes for the nuclide to become stable. This is calculated using atom mass, atomic numbers and decay equations.
What’s the difference between artificial transmutation and natural radioactive decay?
Artificial transmutation is caused via nuclear bombardment to change an isotope into the isotope of a DIFFERENT element. This is firing a small particle at the nucleus, forcing radioactive decay.
Natural radioactive decay is when an isotope stabilizes itself via alpha or beta decay.
Define half-life
Is the time taken for exactly half of the original number of nuclei to decay. It indicates stability and is constant, meaning it will never change.
Define mass defect
difference between mass of intact nucleus and the sum of masses of individual nucleons
