gcse physics - atomic structure

I hate physics 😔

what did John dalton think the atom looked like?

a tiny, indivisible, solid sphere.

what did JJ Thompson think the atom looked like?

the plum pudding model.

A ball of positive charge with negatively charged electrons stuck in it.

what experiment did Ernest Rutherford do?

He did the experiment where alpha particles were shot at gold foil. Most went through and some were deflected.

what did Ernest Rutherford think the atom looked like?

He thought atoms were mostly empty space with a positively charged nucleus surrounded by a cloud of negatively charged electrons.

what did Niels Bohr think the atom looked like?

electrons orbit the nucleus in distinct energy levels

what did James Chadwick discover?

neutrons

what is an isotope?

same number of protons different number of neutrons

what do radioactive nuclei do to become more stable?

emit radiation

what does the random nature of radioactive decay mean?

you can’t predict which individual nuclei will decay and when

what is activity?

the rate at which a source decays

what is a higher activity?

radiation is emitted rapidly over a short time

what is a low activity?

radiation is emitted gradually over a long time

what is the unit of activity?

becquerels

what detects radiation?

Geiger-Muller tube

what is half life?

the average time it takes for the number of radioactive nuclei in an isotope to half

Cobalt-60 has a half-life of 5.3 years. If I have 0.25g now, how much was there when I originally bought the sample 10.6 years ago?

1 gram

what is ionisation?

when an atom loses or gains electrons it becomes an ion that has an overall charge

charge of alpha radiation

+2

charge of beta radiation

-1

charge of gamma radiation

0

mass of an alpha particle

+4

mass of a beta particle

negligible

mass of gamma radiation

0

penetration of alpha radiation

low

penetration of beta radiation

medium

penetration of gamma radiation

high

range of alpha radiation in air

3-5cm

range of beta radiation in air

30 cm

range of gamma radiation in air

over a km

what is alpha radiation?

a helium nucleus

what is beta radiation?

an electron

what is gamma radiation?

an electromagnetic wave

ionising ability of alpha radiation

high

ionising ability of beta radiation

medium

ionising ability of gamma radiation

low

what can stop alpha radiation?

a sheet of paper

what can stop beta radiation?

a few mm of aluminium

what can stop gamma radiation?

a few cm of lead