Model of the atom showing that negative electrons are embedded in a ball of positive charge.

A stream of positive alpha particles fired through a thin piece of gold foil. This lead to an update of the atomic model, from the plum pudding model to nuclear model.

Model of the atom with a small positive charge in the centre surrounded by a cloud of orbiting electrons. The atom is mostly empty space.

Developing a model for atoms

Chemistry

In the Calculations involving mass unit, pupils will learn about calculating the relative formula mass of reactants and products in balanced chemical reactions, and the conservation of atoms and mass, as well as the concept of moles (HT only).

In the Patterns in the periodic table unit, pupils learnt how the chemical and physical properties of different elements are indicated by their position on the periodic table and about key groups of elements. 

Atomic structure and the periodic table

Which scientist is credited with the plum pudding model of the atom?

Place the following atomic models in the order they were proposed, starting with the model first proposed:

Electrons orbit the nucleus in fixed paths.

The atom is mostly empty space with a dense centre.

Negative electrons are scattered throughout a positive sphere.

What does the nuclear model of the atom suggest?

True or False? Chadwick’s contribution to the atomic model was the discovery of the neutron.

Which of the following experiments disproved the plum pudding model?

Atom is a ball of positive charge with embedded electrons.

Dense nucleus surrounded by orbiting electrons.

Match the description to the correct atomic model term.

What are the three main subatomic particles found in an atom?

Which of the following particles is negatively charged?

True or false? Protons and electrons have equal but opposite charges. 

{{}}, along with protons, make up the nucleus of an atom. They add to the mass of an atom but do not carry a charge.

According to the principles of electricity and magnetism, what happens when two electrons come close to each other?

True or false? Neutrons have a greater mass than protons.

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