Chapter 7 - Physics Flashcards
What does a radioactive substance contain?
Unstable nuclei that become stable by emitting radiation.
What are the three types of radiation from radioactive substances?
Alpha, beta and gamma.
What type of event is radioactive decay?
It is a random event - you can’t predict or influence when it will happen.
What do radioactive sources emit?
Alpha, Beta and Gamma.
What type of particles did Rutherford use to probe inside atoms?
Alpha particles.
What could the plum pudding model not explain?
They could not explain why some alpha particles were scattered through large angles.
What charge does an atom have?
It has a small positively charged central nucleus where most of the atom’s mass is located.
What does the nuclear model of the atom explain?
Why some alpha particles scattered through large angles
What are isotopes of an element?
They are atoms with the same amount of protons and different number of neutrons.
What is alpha radiation stopped by?
It’s stopped by paper and has a range of a few centimetres in air.
What is Beta radiation stopped by?
It is stopped by a thin sheet of metal and has a range of about one metre in air.
What is Gamma radiation stopped by?
It is stopped by a thick lead and has an unlimited range in air.
What is the half-life of a radioactive isotope?
It is the average time it takes for the number of nuclei of the isotope in a sample to halve
