Chemistry: Atomic Theory Scientists - Last Group

Ernest Rutherford

Used the gold foil experiment; fired negative ions at a thin sheet of gold foil, discovered the atomic nucleus and proposed a nuclear model of the atom

What was included in Rutherford's model?

A dense positive nucleus, mostly empty space, and negative electrons

What was the issue with Rutherford's model?

The negative electrons should go to the positive nucleus

Neils Bohr

Revised on Rutherford's work by stating electrons are on fixed energy orbitals; developed the planetary/solar system model of the atom

What was included in Bohr's model?

A dense positive nucleus, fixed energy orbitals (rings), and negative electrons

What did Bohr believe?

When an electron absorbs energy, it becomes "excited," when it loses energy, it "relaxes," since it loses exact energy amounts, he assigned energy levels as rings. He also said there are an infinite number of rings, therefore an infinite number of energy levels.

What was the issue with Bohr's model?

Physicists stated that we will never know the exact position of an electron, so they can't be on fixed rings.

What is the Electron Cloud Model?

A nucleus surrounded by a cloud with electrons in energy levels

What are the energy levels of electrons?

Further away from the nucleus, they are higher; closer towards, they are lower