atomic physics

isotope

an atom with the same number of protons but different amount of neutrons

ion

charged particles with different numbers of protons and electrons, creating positive or negative charge (loss of e = p, gain of e = n)

background radiation

mostly natural radiation that is always present in the environment

what is the name of the number circled?

mass number/atomic mass

what is the atomic mass/mass number?

the amount of protons and neutrons in an atom

what is the name of the number circled?

the atomic number

what is the atomic number?

the atomic number is the amount of protons (and electrons) in an atom

name two types of man-made background radiation

any two from -

medical usage

fallout from nuclear weapons tests

nuclear power discharges

non-medical industry usage (eg nuclear power plant emissions)

name two types of natural background radiation

any two from -

radon in atmosphere

grounds and buildings

food and drink

cosmic rays

name two ways to keep safe whilst handling radioactive material

any two from -

wearing a special badge which shows amount of radioactive exposure

using gloves and tongs

direct sources in safe direction

put away sources in lead-lined box (when not in use)

what device is used to count the amount of radioactive particles present?

Geiger-Muller tube (G-M)

what is the mass and charge of an alpha particle

mass - 4

charge +2

what is the speed and range of an alpha particle

speed - 0.1 x speed of light

range - ~6cm

what is the mass and charge of a beta particle

mass - 1/2000

charge - -1

what is the speed and range of a beta particle

speed - 0.9 x speed of light

range - ~50cm

what is the mass and charge of a gamma ray

it has none

what is the speed and range of a gamma ray

speed - speed of light

range - almost infinite

why is a gamma ray different to an alpha and beta particle

a gamma ray is an electromagnetic wave (from the nucleus), whilst alpha and beta are particles

an alpha particle is the same as a..

helium nucleus

list the three types of radiation from most to least ionising

alpha → beta → gamma

list the three types of radiation from most penetrating to least penetrating

gamma →beta→alpha

a beta particle is the same as an..

electron

count-rate

number of decays recorded each second by a detector (eg G-M)

activity

the rate at which a source of unstable nuclei decays

measured in Becquerels (Bq)

how is alpha represented in a nuclear equation?

how is beta represented in a nuclear equation?

how is gamma represented in a nuclear equation?

radioactive decay is..

random

half-life

the time it takes for the number of nuclei of a (radioactive) isotope in a sample to halve

OR

the time it takes for the count rate (or activity) from a sample containing the isotope to halve

the shorter the half life..

the faster the decay

A radioactive isotope has a half life of 45 seconds.

If I initially have 480 particles, how long will it take for the sample to

decay to 30 particles?

30/480 = 1/16 = 1/2⁴

45 × 4 = 180s