P7 Flashcards
Who first discovered the atom
John Dalton
JJ Thomson suggested what?
The plum pudding model
Who did the gold foil experiment?
Ernest Rutherford
What does the gold foil experiment tell us?
Mass is concentrated in the centre and the nucleus is charged. Most of the atom is empty space
Who theorised the electrons were arranged in shells?
Niels Bohr
Who discovered neutrons in the nucleus?
James Chadwick
What is an isotope?
An isotope is an element with the same number of protons but a different number of neutrons. They have the same atomic number but different mass numbers
What is a beta particle?
A fast-moving electron
Beta particles stop at what?
Aluminium
What is a alpha particle?
Two protons and two neutrons
What does an alpha particle stop at?
Skin and paper
What radiation is highly ionising?
Alpha particles
What is gamma radiation?
It is a wave
What stops gamma waves?
Thick lead or a metre of concrete
What happens when an isotope is unstable?
It decays and gives out radiation
