7.2 Flashcards
Who discovered that atoms were divisible?
John Thomson. He proposed the Thomson plum pudding model.
What are the smaller particles that atoms are made up of?
Negatively charged electrons.
How did Ernest Rutherford’s experiment (1911) work?
A stream of radioactive particles was fired at a very thin layer of gold.
How was Rutherford’s experiment recorded?
Detectors were set up around the gold foil to identify if the alpha particles had gone through or deflected.
What was the evidence in Rutherford’s experiment?
Most alpha particles passed through.
Some fast-moving high energy alpha particles were bounced back.
What did Rutherford conclude?
Atoms must contain a lot of space, of which some part contains a large amount of positive charge - the nucleus
What is the difference between Protons, Neutrons and Electrons?
Protons - positive electric charge
Neutrons - mass but no electric charge
Electrons - negative electric charge
What does an atom being neutral mean?
No. of Protons = No. of Electrons
Where are Protons, Neutrons and Electrons located?
Protons and neutrons form a cluster located at the centre of the
atom.
Electrons surround the nucleus.
