P7- Radioactivity Flashcards
(10 cards)
when is an atom radioactive
An atom is radioactive when its nucleus is unstable
how do unstable nucleus become less unstable
Unstable nuclei become stable or LESS unstable by releasing alpha, beta or gamma radiation
what is it called when nan atom emits radiation
When an atom emits radiation, it is called radioactive decay
Radioactive decay is RANDOM
who did the gold foil experiment
Gold foil experiment was conducted by Rutherford, Geiger and Marsden
where was the apparatus set (gold foil)
Apparatus was set in a vacuum ⟶ so that the alpha particles don’t get absorbed into the air
what was the observations (gold foil)
Results/Observation:
most of the alpha particles passed straight through the gold foil
number of deflections/minute decreased as the angle of reflection increased
a very very small number number of particles were deflected by a large amount of(greater than 90 degrees)
what was the meaning of the observations (gold foil)
MEANING of the observations:
most of the atom is empty space
The nucleus is positively charged (as the alpha particle is also positively charged, that’s why whenever it went near the nucleus, it would get deflected, because of the repelling force)
The nucleus is very small and a dense centre of positive charge
Proved the plum pudding wrong
what is a alpha particle known as
An alpha particle is a helium nucleus
what happens in beta decay
In beta decay, a neutron becomes an proton and high speed electron, and the high speed electron (which is your beta particle) is emitted
what happens in alpha decay
In alpha decay, an alpha particle is emitted from the nucleus
