model suggested that the was a Mains ball of positive charge with negative electrons Aiming for Grade 8 LOs: Letter (20 minutes) Split the class into five groups and give them a WebQuest: Models embedded in it. scientist from Dalton, Thomson, Rutherford, Bohr, and Chadwick. Ask of the atom over Justify why the model of the atom has The results from the alpha scattering students to a letter as one of the famous scientists to explain what time. changed over time. experiments of Geiger and Marsden led to the they have discovered and how they think this affects the model of the Evaluate the current model of an atom. plum-pudding model being replaced by the atom. You may wish to the paper using used tea bags, or singe ‘age’ nuclear model. the edges with a candle flame. Niels Bohr adapted the nuclear model by Developing the atomic model (20 minutes) Ask students to make a suggesting that electrons orbit the nucleus at timeline to show the development of the atomic model. They should specific distances. The theoretical calculations of include a labelled diagram of the model, the name of the scientist who Bohr agreed with experimental observations. suggested it, and the date. Later experiments led to the idea that the Plenaries positive charge of any nucleus could be subdivided into a whole number of smaller History of the atom (10 minutes) Interactive where students match particles, each particle having the same amount the scientist with their discovery then complete a paragraph on how of positive charge. The name proton was given the atom was discovered. to these particles. Evidence (10 minutes) Ask students to summarise where the In 1932 the experimental work of James evidence for the nuclear model has come from. Chadwick provided the evidence to show the Electron high voltage experiments on gases. existence of neutrons within the nucleus. • – Nucleus alpha (positively charge) radiation reflected by gold foil • – Students should be able to: (showing a positive, dense centre to the atom). Electron shells given out by heated atoms had specific energy. • – describe why the new evidence from the • Neutrons explained the different masses of elements. • – scattering experiment led to a change in the Experimentalevidence was not found until the early 1930s. atomic describe the difference between the • model of the atom and the nuclear model of the atom. Details of experimental work supporting the Bohr model are not required. Details of alpha particle scattering experiments are not required. Details of Chadwick’s experimental work are not required.
model suggested that the was a ball of positive charge with negative electrons embedded in it. The results from the alpha scattering experiments of Geiger and Marsden led to the plum-pudding model being replaced by the nuclear model. Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations. Later experiments led to the idea that the positive charge of any nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles. In 1932 the experimental work of James Chadwick provided the evidence to show the existence of neutrons within the nucleus. Students should be able to: • describe why the new evidence from the scattering experiment led to a change in the atomic • describe the difference between the model of the atom and the nuclear model of the atom. Details of experimental work supporting the Bohr model are not required. Details of alpha particle scattering experiments are not required. Details of Chadwick’s experimental work are not required. Mains Letter (20 minutes) Split the class into five groups and give them a scientist from Dalton, Thomson, Rutherford, Bohr, and Chadwick. Ask students to a letter as one of the famous scientists to explain what they have discovered and how they think this affects the model of the atom. You may wish to ‘age’ the paper using used tea bags, or singe the edges with a candle flame. Developing the atomic model (20 minutes) Ask students to make a timeline to show the development of the atomic model. They should include a labelled diagram of the model, the name of the scientist who suggested it, and the date. Plenaries History of the atom (10 minutes) Interactive where students match the scientist with their discovery then complete a paragraph on how the atom was discovered. Evidence (10 minutes) Ask students to summarise where the evidence for the nuclear model has come from. • Electron – high voltage experiments on gases. • Nucleus – alpha (positively charge) radiation reflected by gold foil (showing a positive, dense centre to the atom). • Electron shells – given out by heated atoms had specific energy. • Neutrons – explained the different masses of elements. Experimentalevidence was not found until the early 1930s. WebQuest: Models of the atom over time. Aiming for Grade 8 LOs: Justify why the model of the atom has changed over time. Evaluate the current model of an atom.