Nuclear Flashcards
What did Rutherford’s alpha scattering experiment show?
It showed that atoms have a small, dense, positively charged nucleus. Most alpha particles passed through, but some were deflected, disproving the plum pudding model.
What is the nuclear model of the atom?
A model where a small, dense nucleus contains protons and neutrons, and electrons orbit around it. It replaced the plum pudding model.
What is radioactive decay?
It is a random process where unstable atomic nuclei release radiation to become more stable.
What are the three main types of ionising radiation?
Alpha particles (2 protons, 2 neutrons), beta particles (fast-moving electron), and gamma rays (high-energy electromagnetic wave).
What happens to the nucleus during alpha decay?
The nucleus loses 2 protons and 2 neutrons. This decreases atomic number by 2 and mass number by 4.
What happens to the nucleus during beta decay?
A neutron changes into a proton, and a beta particle (electron) is emitted. The atomic number increases by 1.
What are the properties of alpha radiation?
Strongly ionising, weakly penetrating, stopped by paper or skin, travels only a few centimetres in air.
What are the properties of beta radiation?
Moderately ionising, medium penetration, stopped by thin aluminium, travels a few metres in air.
What are the properties of gamma radiation?
Weakly ionising, highly penetrating, needs thick lead or concrete to reduce it.
What is ionisation and why is it dangerous?
Ionisation is when radiation knocks electrons off atoms. It can damage cells or DNA, causing mutations and cancer.
What is half-life?
Half-life is the time it takes for the number of radioactive nuclei in a sample, or the count rate, to halve.
Why is radioactive decay described as random?
Because it is impossible to predict when any individual nucleus will decay.
How is half-life used in real life?
It is used to choose safe medical tracers and estimate the age of objects in archaeology or geology.
What is background radiation?
Radiation always present in the environment from natural and artificial sources.
What are sources of background radiation?
Natural sources include rocks and cosmic rays. Artificial sources include medical treatments and nuclear industry.
What is the difference between irradiation and contamination?
Irradiation is exposure to radiation, but the object does not become radioactive. Contamination is when radioactive material is on or inside an object.
How can the risk of radiation exposure be reduced?
Using shielding, limiting time near sources, using remote handling tools, and increasing distance.
What are some uses of nuclear radiation in medicine?
Used for diagnosis with tracers and treatment with gamma rays to kill cancer cells.
What are the safety concerns with using radioactive materials?
They can cause long-term health effects like cancer. Proper handling, shielding, and disposal are needed to reduce risks.
Why is peer review important in nuclear science?
It ensures data and theories are checked by other scientists for accuracy before being accepted and published.
