radioactivity, hooke's law, terminal velocity

what is the unit for activity (decays per second)

bacquerel (Bq)

what is the unit for distance ?

centimetre (cm)

what is the unit for time ?

second (s), minute (min), hour (h)

what is the structure of an atom ?

• nucleus containing protons (+) and neutrons (0)

• electrons (-) orbit the nucleus

what does atomic number mean ?

number of protons

what does mass number mean ?

number of protons and neutrons

what does isotopes mean ?

atoms with the same number of protons but different number of neutrons

what are the 3 types of ionising radiation ?

• alpha

• beta

• gamma

what are alpha, beta and gamma radiation ?

they are ionising radiations emitted from unstable nuclei in a random process

what is alpha radiation?

• emitted due to too many protons in the nucleus

• charge: +2

• effect of magnetic field or electric: affected

• short range

• slow speed

• most ionising

• stopped by paper or skin

what is beta radiation ?

• emitted due to too many neutrons

• charge: -1

• effect of magnetic field or electric: affected

• medium range

• medium speed

• medium ionising

• stopped by aluminium

what is gamma radiation?

• emitted due to too much energy in the nucleus

• charge: 0

• effect of magnetic field or electric: not affected

• long range (“unlimited”)

• high speed

• least ionising

• stopped by lead

how do alpha emissions change a nucleus ?

mass: -4

atomic number: -2

how do beta emissions change a nucleus ?

mass: no change

atomic number: +1

how do gamma emissions change a nucleus ?

mass: no change

atomic number: no change

what must be balanced in nuclear equations?

both mass number and atomic number (charge) must be conserved