Physics - Radioactivity

Atomic number

number of protons in the nucleus aka proton number

Mass number

total number of protons and neutrons in the nucleus aka nucleon number

Isotope

atom with same number of protons but different number of neutrons

Unstable

the isotope decays randomly due to the balance of neutrons being wrong

Decay

a random process where unstable isotopes emit alpha, beta, gamma or neutron radiation

Activity

rate at which a source of unstable nuclei decay (Becquerel; Bq)

1 Bq

1 decay per second

Count rate

number of decays recorded each second by a detector

Ionising radiation

any type of radiation capable of turning neutral atoms into ions by colliding with them

Background radiation

low-level ionising radiation that is produced all the time

Half-life

the time it takes for the number of nuclei in a sample of radioactive isotopes/the activity/the count-rate to halve

Irradiation

the deliberate exposure of an object to nuclear radiation. The irradiated object DOES NOT become radioactive

Contamination

when an object accidentally comes IN CONTACT with a radioactive substance/unwanted presence of radioactive substances on other materials

Radioactive

isotopes’ nuclei decay and release radiation

Alpha radiation emits:

helium nucleus - nucleus loses 2 protons + 2 electrons

Alpha Ionising ability

High - large size means bump into lots of atoms

Alpha penetrating power

Low - large size means stopped quickly

Alpha radiation stopped by

Thick sheet of paper

Alpha magnetic/electric fields

Positively charged - deflected

Alpha uses

Smoke detector, static eliminators