Contribution
Who showed that common substances always broke down into the same element.
John Dalton
This subatomic particle is neutral, or has no charge.
Neutron
The sum of protons and neutrons in the nucleus of an atom.
What is mass number?
Who discovered the electron.
J.J. Thomson
The two sub-atomic particles that make up the nucleus.
Protons & Neutrons
The number of protons in an atom of a certain element.
What is atomic number?
Who concluded that atoms consist largely of empty space with just a few electrons and with most of the mass concentrated in the center.
Ernest Rutherford
A subatomic particle with a positive charge.
Protons
Mass number - atomic number =_______
What is the number of neutrons?
Who concluded that electrons orbit the nucleus at fixed energies and distances, able to jump from one level to the other, but not to exist in the empty space between them.
Niels Bohr
A subatomic particle with a negative charge.
Electron
Mass - Atomic Number = ______
Neutrons
Who discovered the neutron.
James Chadwick
A subatomic particle with no charge.
Neutron
Atomic Number = Electrons = ______
Protons