What Is Radioactivity? Flashcards Preview

Physics Module 4 > What Is Radioactivity? > Flashcards

Flashcards in What Is Radioactivity? Deck (12):
1

What causes radioactivity to decrease?

Time

2

What does nuclear radiation do to materials?

It ionises materials

3

Where does the radiation of an atom come from?

The nucleus

4

Describe radioactive substances

They decay naturally and give out radiation in the form of alpha, beta and gamma

5

Explain half-life

It is the time it takes for half the undecayed nuclei in a radioactive substance to decay.

6

Explain ionisation

- removal or electrons from particles
- gain of electrons by particles

7

Explain why alpha particles are such good ionisers

Because they are relatively massive so they hit atoms hard enough to strip off electrons

8

What is an alpha particle?

A helium nucleus

9

What is a beta particle?

A fast moving electron

10

Describe what happens to a nucleus when an alpha particle is emitted

- mass number decreases by 4
- nucleus has two fewer electrons
- nucleus has two fewer protons
- atomic number decreases by 2
- new element formed

11

Describe what happens to a nucleus when a beta particle is emitted

- mass number is unchanged
- nucleus has one less neutron
- nucleus has one more proton
- atomic number increases by one
- new element formed

12

What is the radioactivity ir activity of an object measured by

The number of nuclear decays emitted per second