P19: Radioactivity Flashcards
1
Q
Why do some atoms emit radiation?
A
Because they have unstable uncle that can only stabilise by emitting radiation.
2
Q
3 types of radiation
A
Alpha
Beta
Gamma
3
Q
Relative mass of protons
A
1
4
Q
Relative mass of neutrons
A
1
5
Q
Relative mass of electrons
A
1/2000
6
Q
Alpha Radiation
A
α 2 protons + 2 neutrons. Relative mass of 4 Stopped by paper 5 cm range in air Greatest ionising power
7
Q
Beta Radiation
A
B Relative mass of 0 Charge of -1 A neutron in the nucleus changes into a proton and an electron. The electron is expelled from the atom but the proton stays. Stopped by aluminium 1m range in air Medium ionising power
8
Q
Gamma Radiation
A
Y Uncharged and has no mass- is a form of electromagnetic radiation. Doesn't change the element etc. stopped by lead. Unlimited range in air. Least ionising power.
9
Q
Half Life
A
The time it takes for the number of nuclei of the isotope in a sample to halve.
10
Q
What halves every half life?
A
The no. of atoms of a radioactive isotope
+
The count rate.
