C1 - Alpha Scattering Experiment

What did the ancient Greeks believe about atoms?

That atoms were tiny, indivisible spheres.

What discovery in 1897 changed our view of atoms?

The discovery of the electron.

What did the discovery of electrons prove about atoms?

That atoms have internal structure and are not indivisible.

What model of the atom came after the discovery of electrons?

The Plum Pudding Model.

What is the Plum Pudding Model?

A model where atoms are spheres of positive charge with negative electrons embedded in them.

Why is it called the "Plum Pudding" Model?

Because it resembles a traditional pudding with plums (electrons) in a sponge (positive charge).

What was the experiment used to test the Plum Pudding Model?

The Alpha Scattering Experiment (also called Rutherford's Gold Foil Experiment).

What material was used in the alpha scattering experiment?

Thin gold foil.

Why was gold used in the experiment?

Because it can be hammered into very thin sheets, only a few atoms thick.

What particles were fired at the gold foil?

Alpha particles.

What is the charge of an alpha particle?

Positive.

What did most alpha particles do when fired at the gold foil?

They passed straight through.

What did the scientists conclude from most alpha particles passing through?

That atoms are mostly empty space.

What happened to some alpha particles in the experiment?

They were deflected (changed direction).

What caused alpha particles to be deflected?

The presence of a small, positively charged center in the atom.

What happened to a few alpha particles in the experiment?

They bounced straight back.

What did the scientists conclude from alpha particles bouncing back?

That the center of the atom is very dense and contains most of the atom's mass.

What did the alpha scattering experiment disprove?

The Plum Pudding Model.

What model replaced the Plum Pudding Model?

The Nuclear Model.

What is the Nuclear Model of the atom?

A model where a tiny, dense, positively charged nucleus is at the center, with electrons around it and mostly empty space.

What part of the atom contains most of the mass?

The nucleus.

Where are the electrons located in the nuclear model?

Orbiting around the nucleus.

How did the experiment prove that atoms are mostly empty space?

Because most alpha particles passed straight through the gold foil.

Why were some alpha particles deflected?

Because they came close to the positively charged nucleus and were repelled.

Why did some alpha particles bounce straight back?

Because they hit the dense nucleus head-on.

What does the nuclear model explain that the plum pudding model couldn't?

The deflections and reflections of alpha particles.

What charge