Lecture One Flashcards
What did Dalton discover?
The atom
What did J. J. Thomson discover?
He discovered the ‘cathode rays’ in a discharged tube. These rays are a stream of negatively charged particles (electrons).
Coined the ‘plum pudding’ theory of the structure of the atom.
He was also responsible for discovering how to find the mass-to-charge ratio of an electron.
What did Millikan discover?
How to measure the charge of an electron.
What did Bacquerel and the Curies investigate?
They investigated radioacrtivity.
What did Rutherford discover and what was his experiment?
Discovered three different types of radiation:
- α particle (alpha)
- β particle (beta)
- γ rays (gamma)
Rutherford’s experiment involved firing a beam of alpha rays at a think gold foil.
Most particles passed though it, but some back-scattered.
He concluded from these findings that:
- Majority of the mass and positive charge of an atom if found in an extremly small and dense ‘nucleus.’
- Most of the volume of an atom is empty space in which electrons move.
What did Mass Spectroscopy reveal about atoms?
It revealed that some atoms have isotopes.
Isotopes are atoms with the same atomic number, but different mass numbers. That is, have the same number of protons and electrons, but a different number of neutrons.
What are the masses of the sub-atomic particles?
Proton: 1.0073u
Neutron: 1.0087u
Electron: 5.486 × 10 ^ -4u
Define atomic number.
The number of protons in the nucleus.
Define mass number.
The total number of protons and neutrons.
What is the notation for representing mass and atomic numbers?
