P2.6 Flashcards
What is a radioactive substances?
Atom with an unstable nucleus.
What types of radiation are given out from a radioactive substance?
- alpha radiation
- beta radiation
- gamma radiation
- background radiation
When does an unstable nucleus decay?
When it emits radiation.
Where does background radiation come from?
- the environment
- from space
- from devices such as X-Ray tubes
When will an unstable nucleus decay?
It’s a random event that happens without anything being done to the nucleus.
Name a radioactive element:
Polonium
How was the nuclear model of the atom established?
Rutherford used his theory to estimate the diameter of the nucleus and then it was quickly accepted.
Why was the plum pudding model of the atom rejected?
Because it couldn’t explain why some alpha particles were scattered through large angles.
What did the nuclear model of the atom explain?
Explained why the alpha particles are scattered and why some are scattered through large angles.
What is an isotope?
Atoms of the same element with different numbers of neutrons.
How does the nucleus of an atom change when it emits an alpha particle or a beta particle?
Alpha- its atomic number goes down by 2and its mass number goes down by 4
Beta- the atomic number goes up by 1 and its mass number stays the same
What happens to gamma radiation when it’s spreads out in air without being absorbed?
It gets weaker.
How can we separate radiations?
By using a magnetic field or an electric field.
How is alpha radiation stopped?
Stopped by paper each composed of two protons and two neutrons.
How is beta radiation stopped?
Stopped by thin metal and consists of fast moving electrons emitted from the nucleus.
