The Development of the model of atom GCSE combined science physics edexel higher

Discovery of protons, neutrons and electrons

What did Henri Becquerel discovered?

Radioactivity. Some rocks contain atoms whose nuclei break up and give out invisible emmissions.

What year did Becquerel discovered radioactivity?

1896.

Who discovered electrons and what year?

In 1897, J.J Thomson discovered electron

What was J.J Thomson’s evidence?

Used cathode-ray tube. Identified a negative charge subatomic particle. Atoms are divisible.

What J.J Thomson’s model?

Plum pudding model.

Who discovered nucleus and what year?

Ernest Rutherford discovered nucleus in 1909.

What was Ernest Rutherford’s evidence?

Shot a beam of positively charged particles at a thin sheet of gold foil. Some particles were scattered, few deflected.

What was Ernest Rutherford’s model?

Rutherford’s model.

What did Rutherford say about the atoms?

Most of the atoms are empty space.

Who discovered protons and nucleus and what year?

Rutherford discovered protons and nucleus in 1920.

What was his evidence?

Large neutral particle within the nucleus. His ideas is based on different atomic mass and the atomic number of atoms. Continued scattering experiment.

Who discovered neutron and what year?

In 1932 James Chadwick discovered neutron.

What was his evidence?

Provided evidence for the existence of these neutral. Particles which were neutrons

Who developed the nuclear model and what year?

In 1913, Neil’s Bohr developed the nuclear model.

Why did he developed the nuclear model?

Electrons have fixed energy shells.

What was Neil Bohr’s evidence?

Emission spectra.

What did John Dalton do in 1803?

Presented his atomic theories.

What was Dalton’s theory?

Atoms which are tiny particles cannot be created, destroyed or divided. Atoms of the same elements are identical and atoms of the different elements are different.

Describe the plum pudding model?

Negatively charge electrons must be scattered over a large positive blob.

Give 2 main changes to the atomic model the alpha scattering experiment resulted in.

Mass concentrated in centre (nucleus) and positive charge at the centre.

Who explained how electrons orbit the nucleus?

Neil’s Bohr.

Who discovered the existence of the neutron?

James Chadwick.

What particles are found in the neutron?

Protons and neutrons.

What are electrons found in?

Shells.

Which particle did James Chadwick discover?

Neutrons.

Most particles past through.

Particles went through the gold foil because most of the atoms is empty space.

Some would be deflected.

The centre is positively charged.

A few would bounce back.

Centre is dense and is a nucleus.

What was Dalton’s model?

Billiard ball model.