Atomic Model--Timeline of the Atom

This was the first model of the atom ever proposed. It was simple and described atoms as tiny spheres that could not be broken down into smaller pieces.

• Democritus's model of the atom
• The "Plum Pudding Model" of the atom
• The "Rutherford Model" of the atom
• The "Quantum Mechanical Model" of the atom

Ernest Rutherford discovered that atoms were mostly _________________. 

• negatively charged
• positively charged
• electrons
• empty space. 

Discovered the electron using cathode ray tube

• Joseph Thomson
• John Dalton
• Ernest Rutherford
• Robert Millikan

Idea was of an indivisible particle of matter he called "atomos"

• John Dalton
• Aristotle
• Democritus
• Plato

What contribution did John Dalton make to atomic theory? 

• He discovered that every atom was positively charged. 
• He discovered that every element consisted of one type of atom.  
• He discovered that atoms had nuclei. 
• He discovered that atoms could be divided into smaller parts. 

J.J. Thomson provided evidence that an atom...

• is the smallest particle of matter
• contains negatively charged particles
• has an overall negative charge
• has an overall positive charge

First measured the mass and charge of an electron

• Joseph Thomson
• Robert Millikan
• John Dalton
• Niels Bohr

His atomic model was depicted similar to a planetary/solar system

• Niels Bohr
• Joseph Thomson
• Ernest Rutherford

Rutherford concluded that the atom

• has a nucleus with a positive charge
• has a nucleus with a negative charge 
• is a small mass with negative and positive charges
• contains a nucleus without a charge

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He determined the mass of an electron and confirmed it’s charge in 1909 as a result of oil drop experiments.

• Thompson
• Chadwick
• Millikan
• Democritus