The History of the Atom

At the start of the ________ described atoms as solid spheres and said that different sphere made up the different elements.

________ proposed that electrons orbit the nucleus in fixed shells and arent anywhere in between.

In 1909 ________ and his student Ernest Marden conducted the famous alpha particle scattering experiments.

________ was supported by many experiments and it helped to explain lots of other scientists observations at the time.

Each ________ is a fixed distance from the nucleus.

the nuclear model of the atom

the atom is a ball of positive charge with electrons embedded in it

atoms as solid spheres

J J Thompson

electrons orbit the nucleus in fixed shells and distances, and aren't anywhere in between

They fired positively charged alpha particles at an extremely thin sheet of gold

When alpha particles cam near the concentrated, positive charge of the nucleus, they were deflected. If they were fired directly at the nucleus,they were deflected backwards. Otherwise, they passed through the empty space

a cloud of negative electrons surround the nucleus, and most of the atom is empty space. Electrons are randomly placed

Ernest Rutherford and Ernest Marsden

his measurements of charge and mass showed an atom must contain even smaller, negatively charged particles, electrons

Provided evidence for neutral particles in the nucleus, called neutrons

Showed that the nucleus can be divided into smaller particles, which each have the same charge as a hydrogen nucleus, called protons

John Dalton - plum pudding model - nuclear model - bohr nuclear model - modern nuclear model

John Dalton - J J Thompson - Ernest Rutherford - Niels Bohr - James Chadwick

Nucleus is in the centre of the atom and electrons orbit the nucleus in shells