Physics: atomic structure and radioactivity

The radius of an atom is 1 x 10(-10) and the nucleus is about 1/10000 of this

Electrons can change energy levels when an atom [blank_start]absorbs[blank_end] electromagnetic radiation so the electrons moves from a [blank_start]lower[blank_end] energy level to a [blank_start]higher[blank_end] on. If the atom [blank_start]emits[blank_end] electromagnetic radiation so the electron returns to its [blank_start]original[blank_end] energy level

What does the mass number represent?

Isotopes are the same element but with a different number of [blank_start]neutrons [blank_end]

Ancient Greeks->1897->Plum pudding model->Alpha scattering experiment->Nuclear model->Niels Bohr->James Chadwick

Some isotopes have an [blank_start]unstable[blank_end] nucleus so to become [blank_start]stable[blank_end] the nucleus gives out [blank_start]radiation[blank_end] - radioactive decay ( a [blank_start]random[blank_end] process)

The rate at which a source of [blank_start]unstable[blank_end] nuclei [blank_start]decay[blank_end]. Which is measured using a [blank_start]Geiger[blank_end]-muller tube.

Alpha particles—>

Beta particle—>

Gamma radiation—>

Nuclear equations- alpha decay, atomic number decreases by [blank_start]2[blank_end] and the mass number by [blank_start]4[blank_end]

Nuclear equations- Beta decay, the atomic number [blank_start]increases[blank_end] by [blank_start]1[blank_end] and the [blank_start]mass[blank_end] number doesn’t change

Half life- the time it takes for the count rate or activity (number of decay per second) from a sample contains the isotope to fall to half its initial level.

Radiation cannot be ionising (form charge ions)

[blank_start]Irradiation[blank_end] is exposing an object to nuclear radiation like [blank_start]sterilisation[blank_end] which uses [blank_start]gamma[blank_end] radiation.

Ionising radiation decreases the risk of cancer

Precautions when using ionising radiation include...

Alpha radiation is [blank_start]strongly[blank_end] ionising. It can be stopped by dead skin cells and alpha emitters can be dangerous if inhaled or swallowed.

Beta radiation is [blank_start]less[blank_end] ionising. It can penetrate skin.

Gamma radiation is [blank_start]weakly[blank_end] ionising. Can penetrate the body but likely to pass through.

A tracer must...

Gamma rays through radiotherapy can pass into the body and destroy a tumour