Studied by 5 peopleWho coined the term, atom?
Democritus
What did Democritus think about atoms in regards to how they were different from object to object?
He thought that each object had its own atom
Is Dalton’s first postulate true or false: elements are composed of atoms.
True
In his second postulate, Dalton says all atoms of a given element are identical. Is this true or false?
False
In his second postulate, Dalton says atoms of different elements are different. Is this true or false?
True
Which subatomic particle gives an element identity?
Proton
In his third postulate, Dalton says that compounds are composed of more than one element. T/F?
True
In his third postulate, Dalton says that the ratio of particles in an element are an integer or a fraction. T/F?
True
In his fourth postulate, Dalton says that a chemical reaction involves the separation, combination, or rearrangement of atoms without creating or destroying mass. T/F?
True
What is the Law of definite proportions?
In a compound, the ratios of elements is always the same
What is the Law of multiple proportions?
If multiple atoms occur in different compounds, then adding the mass of the elements in each compound will form ratios of small whole numbers.
What is the law of conservation of mass?
Mass cannot be created nor destroyed
What particle did JJ Thompson discover?
Electrons
What ratio did JJ Thompson discover?
Charge-to-mass ratio
When JJ placed positive and negative charges, the electrons bended towards which?
Positive
What model did JJ create?
Plum Pudding Model
What did Crooke add to his experiment compared to JJ?
He added a pinwheel
What did Crooke prove with his experiment?
Electrons have mass
Would Crooke agree with the Plum Pudding Model?
Yes
What numerical value did Millikan figure out?
He found the magnitude of the charge of an electron
Millikan used a positive plate to counteract gravity. This was placed in a chamber with electrons that would stick to _____ droplets (what material)?
oil
Millikan would increase the charge of the positive plate until some droplets were ________
suspended
Millikan determined the total mass of the droplet. Why was it ok for him to not subtract the mass of the electrons?
Electrons have almost no mass
Would Millikan agree with the Plum Pudding Model?
Yes
An alpha particle is made of what?
2 protons and 2 neutrons
Rutherford’s experiment was called…
Gold Foil Experiment
With the plum pudding model, any given positively charged area would have a very weak charge, therefore going through the gold foil. What actually happens?
Some alpha particles bounce off the foil in a random direction
What does Rutherford’s experiment prove about protons?
They aren’t spaced out, but are concentrated densely together.
Approximately how much heavier are protons compared to electrons?
about 1840 times
Would Rutherford agree with plum pudding? if not, what would he change
No, he would add a nucleus
Why did Chadwick conduct his experiment?
He thought there was another subatomic particle contributing to the mass of an atom
Chadwick shot alpha particles through a variation of elements along with what? (term for wax)
Paraffin
What did Chadwick conclude to exist?
neutrons
how does the mass of a neutron compared to a proton?
slightly heavier
Where did chadwick assume the neutron to be located and why?
In the nucleus because neutral charges could stabilize the proton
how can you compare the size of the nucleus to the whole atom?
marble to football stadium
Note
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