P1 and P3 Flashcards
Which Greek philosophers thought that you could eventually cut no more and there would be an atom
Democritus and Leucippus
What was Daltons model?
Discovered in 1870’s.
He was investigating how elements combined.
Daltons model was a very small indestructible sphere
Dalton thought that…
All the atoms in an element are the same
The atoms in one element are different from the atoms in all other elements
What was Thomson’s model?
In 1897, Dalton was investigating cathode rays
He found that cathode rays were made of electrons which must have come from inside the atom.
In 1904, Thomson suggested a new model:
A positive mass with negative electrons embedded in it.
How does the history of the model of the atom link to evidence and idea change?
The history of the atom shows that ideas change when there is new evidence that cannot be explained using old ideas
What is the Rutherford model?
In 1899, Rutherford was investigating alpha particles and fired them at a piece of gold foil.
To explain his results, Rutherford suggested that an atom is made of a small positively charged nucleus with electrons around the outside.
Almost all the mass of an atom is in its nucleus
Describe the Rutherford experiment
Alpha particle source in a lead box with a narrow hole and a fixed thin metal foil in front of it.
The apparatus was placed in a vacuum chamber to prevent air molecules absorbing the alpha particles
The detector was moved to different positions and at each position, they counted the number of spots of lights they saw.
What is the Bohr model?
The problem with Rutherford model was that you would expect the electrons to spiral until they hit the nucleus.
In 1913, Bohr suggested that electrons can only move in fixed or it’s called electron shells around the nucleus
What is the order of magnitude
A number to the power of 10
What is charge?
Charge is a property of matter
How do you produce static electricity
When you rub two insulators together, electrons move from one insulator to the other. One object has extra electrons and one doesn’t have enough to cancel the positive charge.
The charge on each object is static electricity
How do you discharge an object
You need to remove the charge. You connect it to something that allows charge to flow,
What is a spark?
A spark is a flow of charge through the air
What is current?
Current is the rate of flow of charged particles
What is conventional current
When charge moves from the positive terminal of the battery to the negative terminal
