Atomic structure Flashcards
What does the alpha particle experiment show and why?
Most of the atom must be empty as they passed through foil, the nucleus must be positively charged as some were deflected by a big angle and the nucleus must be very small as few were deflected
How big is the radius of an atom?
1 x 10^-10
What is an ion?
A charged particle with extra or less electrons
What is an isotope?
Different forms of the same element; isotopes have atoms with the same number of protons but a different number of neutrons
What happens to an unstable isotope?
They decay other elements and give out radiation
What is radioactive decay
Where unstable isotopes decay into other elements and give out radiation to try to become stable
What is alpha radiation?
When two neutrons and two protons (an alpha particle) are emitted from the nucleus
How does the mass number of an atom change after emitting an alpha particle?
It goes down by four
What are the properties of alpha particles?
Big, slow-moving, strongly ionising and will not penetrate very far
What is a beta particle?
A fast-moving electron
How does a nucleus decay by beta decay?
A neutron turns into a proton and it releases an electron
What are the properties of beta particles?
Quite small, quite fast, moderately ionising and moderately penetrating
What is a gamma ray?
A very short wavelength EM wave that is released by the nucleus
What are the properties of gamma rays?
They are highly penetrating and weakly ionising
What is half-life?
The time it takes for the number of nuclei of a radioactive isotope in a sample to halve
