Radioactivity Flashcards
What is radioactivity?
Radioactivity is a spontaneous breaking up of unstable nuclei with the emission of one or more types of nuclear radiation. Emitted from radioisotopes.
What are radioisotopes?
Radioisotopes are radioactive isotopes. I.e. isotopes with unstable nuclei that in an attempt to become more stable emit nuclear radiation.
How was radioactivity discovered?
Henri Becquerel exposed uranium salts to photographic plates without sunlight and an image still formed. Concluded that the uranium salts must be releasing some form of energy.
Contribution of Pierre and Marie Curie.
Isolated and discovered the radioactive elements polonium and radium from an ore of uranium known as pitchblende.
Properties of alpha radiation?
Helium nucleus (2 protons + 2 neutrons) \+2 charge Weakest penetrating ability. (Paper) Strongest ionising ability. Shortest range.
Properties of Beta Radiation?
A beta particle is an electron -1 charge Moderate penetrating ability. (Aluminium) Moderate ionising ability. Moderate Range.
Properties of Gamma Radiation?
High energy electromagnetic radiation. No charge. Strongest penetration ability (lead) Weakest ionising ability Longest range
What happens when an alpha particle is emitted?
The mass number decreases by four and the atomic number decreases by two.
What happens when a beta particle is emitted?
A neutron in the nucleus splits into a proton and an electron.
The proton remains in the nucleus, but the high energy, high speed electron is ejected out as a beta particle.
What happens when a gamma ray is emitted?
The structure of the nucleus remains the same but it loses energy to become more stable.
Outline three differences between a nuclear and chemical reaction.
Nuclear Reaction: 1. Involves a change in the structure of the nucleus. 2. New element formed. 3. No chemical bonds broken or formed. Chemical Radiation: 1. Involves electrons being transferred or shared. 2. No new element formed. 3. Chemical bonds broken and formed.
Outline the health hazards of nuclear radiation. Which is the most dangerous?
Alpha particles, beta particles and gamma rays can cause cancer.
Gamma rays are the most dangerous as they have the strongest penetrating ability.
What precautions should be taken?
Radioactive material should be stored in a lead container.
Minimise time spent with radioactive material.
Maximise the distance the radioactive material is from you.
Use the proper protective clothing and use tongs to handle radioactive resources.
Give four uses of radioisotopes.
Medical: Cobalt-60 used to destroy cancer cells. Iodine-131 used to destroy overactive thyroid gland.
Archaeology-Carbon-14 used to calculate age of dead organisms.
As it slowly decays the ratio of Carbon-14 to Carbon-12 changes. From this ratio an age can be determined.
Food Irritation-Food can be treated with gamma rays to destroy microorganisms and keep food fresh.
Smoke alarms-Americium-241 emits alpha particles which when absorbed by smoke triggers alarm.
What is background radiation? List 3 sources.
Background radiation is the radiation naturally present in the environment.
- Radon gas emitted from rocks.
- All food eaten. (Plants absorb radioactive material)
- Cosmic Rays from the sun.
