P1.1 Particle Model Flashcards
Atom
Smallest particle of an element that can exist
Made of protons, neutrons and electrons
Bohr model
Small DENSE nucleus surrounded by orbiting electrons with attraction provided by electrostatic forces
Electron
Subatomic particle orbiting the nucleus of an atom
-1 charge
0.0005 or negligible relative mass
Electron shells
Orbits around an atom by electrons in energy levels,
for electrons in the Bohr model
Neutron
Subatomic particle found in nucleus of an atom
No charge
Relative mass of 1
Nucleus
Small dense mass at centre of an atom made of protons and neutrons
Order of magnitude
Number to the nearest power of 10
Increase of 2 orders = multiplying by 100
Plum pudding model
Outdated model
Electrons embedded in a sphere of positive charge
Proton
Subatomic particle in nucleus of the atom
Charge of +1
Relative mass of 1
Rutherford model
Positively charged nucleus and electrons orbit around it
How Rutherford’s observations led him to suggest that an atom has a nucleus
In the alpha particle experiment:
Majority of the alpha particles passed through with little or no deflection so the majority of the atom is empty space/vacuum
Few alpha particles were deflected backwards, showing that there is a small, massive nucleus at the centre
1 in 8000 was scattered through large angles so the mass of the atom is very concentrated at the centre of the atom
This mass (nucleus) is positively charged. This mass (the nucleus) is very small compared to the size of the atom.
There would not be any alpha particles scattered through large angles if the plum pudding model were correct
Diameter of a typical atom
1 x 10 ^ -10 m
Typical radius of a nuclei
10 ^ -15 m
Observations of Rutherford, Geiger, and Marsden’s experiment
Majority of alpha particles passed through with little or no deflection so the majority of the atom is empty space/vacuum
Few alpha particles were deflected backwards, showing that there is a small, massive nucleus at the centre
1 in 8,000 was scattered through large angles
Conclusions from Thomson’s experiments with cathode rays
Cathode rays were made of negatively charged particles - electrons
The particles had a mass smaller than an atom
Atoms were neutral in charge
Difference between the Democritus model of the atom and Dalton’s
There was no scientific equipment to do experiments on atoms
Democritus thought that there were atoms because of a BELIEF he had about the nature of matter
Dalton’s model was a simple solid sphere
The sphere for one element was different from the sphere for another but he did not know how
How does the cathode ray tube work
Metal cross at front is heated to release electrons
These electrons cause fluorescent light
The light can be attracted or repelled using magnets
Cathode is negatively charged to repel electrons to the anode
This is done in a vacuum to avoid collision with air particles
Charge of the cathode and anode
Cathode - negatively charged
Anode - positively charged
Positive
Anode
Negative
Is
Cathode
