What is radioactivity Flashcards
1
Q
Radioactive decay
A
- Radioactive substances decay naturally, giving out α, β, and γ radiation.
- Radioactive decay is a random process; it isn’t possible to predict exactly when a nucleus will decay.
2
Q
What does nuclear radiation cause?
A
Nuclear radiation causes ionisation by removing electrons from atoms or causing them to gain electrons.
3
Q
Radioisotopes
A
- There are so many atoms in even the smallest amount of radioisotope that the average count rate will always be about the same.
- Radioisotopes have unstable nuclei. Their nuclear particles aren’t held together strongly enough.
4
Q
Half-life
A
The half-life of a radioisotope is the average time for half the nuclei present to decay. The half-life cannot be changed.
5
Q
What is a nucleon?
A
A nucleon is a particle found in the nucleus. So, protons and neutrons are nucleons.
6
Q
The nucleus of an atom can be represented as:
A
- A = atomic number (or nucleon number)
- Z = atomic number (or proton number)
- X = chemical symbol for the element
- Z = the number of protons in the nucleus, so the neutron = A-Z
7
Q
What happens an α or β particule is emitted?
A
When an α or a β particule is emitted from the nucleus of an atom, the remaining nucleus is a different element.
8
Q
What are α particles?
A
- α particles are very good ionisers.
- They are the largest particle emitted in radioactive decay. This means they are more likely to strike atoms of the material they are passing through, ionising them.
9
Q
α particul properties
A
- Positively charged
- Has a large mass
- Is a helium nucleus
- Has helium gas around
- Consists of 2 protons and neutrons
10
Q
α particle during decay
A
- Mass number decreases by 4
- Nucleus Has 2 fewer neutrons
- Nucleus has 2 fewer protons
- Atomic decreases by 2
11
Q
β particul properties
A
- Negatively charged
- Has a very small mass
- Travels very fast
- Is an electron
12
Q
β particle during decay
A
- Mass number is unchanged
- Nucleus has one less neutron
- Nucleus has one more proton
- Atomic number increases by one
