C4 Flashcards
isotopes
elements that have same number of pro tons but different number of neutrons.
atomic radius
Atomic radius is the distance from the nucleus to the outermost electron shell.
Decreases across a period (left to right) due to increasing nuclear charge.
Increases down a group due to added electron shells.
ions
ions are charged atoms become charged by losing or gaining electrons from its outer shell
cation- positive charge loses electrons
Anions- negative charge gains electrons
Nuclear decay
Nuclear decay is when unstable atomic nucleus loses energy by emitting radiation.
To achieve a more stable state
forms radioisotopes
radio isotopes
Radioisotopes are unstable isotopes of elements that emit radiation as they decay into stable forms.
Alpha particle
An alpha particle is a type of ionizing radiation emitted during radioactive decay.
Consists of 2 protons and 2 neutrons (same as a helium nucleus).
Positively charged (+2).
Low; can be stopped by paper or skin.
High; strongly interacts with matter, causing significant damage to biological tissues.
Beta particle
A high-energy electron radioactive decay.
beta-minus (β⁻)
β⁻: An electron emitted when a neutron decays into a proton.
Atomic mass stays same
atomic number goes up by 1
More penetrating than alpha particles but less than gamma rays.
penetrates through paper but not through thick materials
Less ionising than alpha but more than gamma
Gamma particle
They are part of the electromagnetic spectrum, similar to X-rays but with much higher energy.
have no mass or charge
Highly penetrable can only be blocked by lead
low ionising
Alpha decay
Alpha decay is a type of radioactive decay where an unstable nucleus emits an alpha particle.
Uranium-238 decays into Thorium-234 by emitting an alpha particle.
atoms atomic number decreases by 2, and its mass number decreases by 4.
Uranium-238 decays into Thorium-234 by emitting an alpha particle.
Beta decay
radioactive decay where a nucleus emits a beta particle.
Changes the atomic number of the element, transforming it into a different element.
Gamma decay
type of radioactive decay where an unstable nucleus releases excess energy in the form of gamma rays
It usually occurs after alpha or beta decay, when the nucleus is in an excited state.
No particles are emitted mass and atomic number are unchanged
ionising radiation
Ionising radiation is radiation with enough energy to remove tightly bound electrons from atoms, creating ions.
nuclear fission
Large nuclei break up
heavy nucleus bombarded with high energy particles
splits into to lighter nuclei with equal mass
nuclear Fussion
small nuclei combine
occurs in sun and star
Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.
Fuel Sources: Typically uses isotopes of hydrogen, like deuterium and tritium
Relative atomic mass
weighted average mass of an atom of an element compared to 1/12th the mass of a carbon-12 atom.
Practical applications of radiation
Alpha- Smoke alarms, cancer treatment
Beta- Cancer treatment, carbon dating, radio therapy
gamma- cancer treatment and sterilization
precautions that must be taken to minimise radiation
Limit time exposed
distance
Sheilding- lead, protective clothing
Why do alpha particles ionise more than gamma and beta
there higher mass
+2 charge allowing them to interact with many electrons
nuclei
Nuclei are the dense positively charged centers of atoms, composed of protons and neutrons, held together by the strong nuclear force.
Bq unit
The unit “Bq” stands for becquerel, which is the SI unit of radioactivity, representing one radioactive decay per second
Geiger counters
A geiger-muller tube detects radiation by ionising gas within the tube, creating a current pulse that’s amplified and counted, indicating the presence and intensity of radiation
back round radiation
Cosmic Radiation – High-energy particles from space that interact with Earth’s atmosphere.
Higher at higher altitudes (e.g., in airplanes or mountains).
Terrestrial Radiation – Radiation from radioactive elements in the Earth’s crust.
Uranium, thorium, and potassium-40 in rocks and soil.
Internal Radiation – Small amounts of radioactive isotopes inside the human body.
Potassium-40 in bones and carbon-14 in tissues.
abundance
Isotopic Abundance – The percentage of a particular isotope of an element compared to the total amount of that element in a sample.
how to control nuclear fission
Methods to Control Fission:
✅ Control Rods – Absorb neutrons (Boron, Cadmium).
✅ Moderators – Slow down neutrons (Water, Graphite).
✅ Coolants – Remove heat (Water, Sodium).
✅ Neutron Poisons – Absorb excess neutrons (Xenon-135, Boric Acid).
✅ Safety Systems – Automatic shutdown (SCRAM), containment structures.
🔹 Goal: Maintain a stable chain reaction & prevent overheating.
Why are neutrons better at causing chain reactions than alpha and beta particles
- Neutrons Are Uncharged
Can easily penetrate nuclei without repulsion.
- Neutrons Induce Fission
Slow neutrons cause fission in heavy elements (e.g., Uranium-235).
- Chain Reaction
Neutrons released from fission trigger more fission events.
- Neutron Moderation
Neutrons can be slowed down for optimal fission.
🔹 Key Point: Neutrons are better at initiating and sustaining chain reactions than alpha and beta particles due to their neutrality and ability to induce fission.
