P4: Atomic Structure (triple) Flashcards
How many times smaller is the size of the nucleus’ radius compared to the whole atom’s radius?
10000 times smaller.
How large is the radius of an atom?
About 1 * 10^-10 m
What happens to unstable isotopes?
They decay into other elements and give out radiation. This is so they can become more stable. They try to balance the number of neutrons and protons or get rid of excess energy.
Describe alpha particles.
Two protons and two neutrons. Like a helium nucleus
Low penetration power
strongly Ionising
Describe beta particles.
Fast moving electrons
Moderately ionising
Moderate penetrating power
Emitted when a neutron breaks down into an electron and proton
Describe gamma rays.
Waves of electromagnetic radiation
Released by a nucleus
High penetration power
Weakly ionising
How are nuclear equations written?
Atom before decay —> atom after decay + radiation emitted
What happens to a nucleus after alpha radiation?
Atomic number reduces by 2
Mass number reduces by 4
Charge decreases
How Does beta decay change the nucleus?
Atomic number increases
Charge increases
Mass doesn’t change
What happens to a nucleus when gamma rays are given off?
No change in mass
No change in charge
This is a way of giving off excess energy
How is the activity of a radioactive substance measured?
In becquerels (Bq) 1 Bq is 1 decay per second
What is irradiation?
Exposure to radiation
What is radioactive contamination?
Radioactive particles getting into objects.
Where does background radiation come from?
Radioactivity of naturally occurring isotopes which are all around us (air, food, building materials and rocks).
Radiation form space (cosmic rays).
Radiation from human activity (fallout form explosions or waste).
What are radioactive isotopes used for in medicine?
they are injected or swallowed by a patient to check body functions involving similar substances. The emitted gamma rays can detected to work out how the substance is being used and moved around the body.
