electrons in their outer shell (outer electrons) and this gives them similar chemical properties. 5.1.2.2 Before the discovery of Describe steps in the 0.5 Put a timeline of the steps that Give students cards with the protons, neutrons and development of the Mendeleev went through into properties and atomic electrons scientists periodic table. the correct order. weights of the elements or attempted to classify the Mendeleev knew about. Ask elements by arranging them Describe and explain how them to place the cards into (interactive) in order of their atomic testing a prediction can a order would classify the weights. support or refute a new properties. University of scientific idea. Nottingham – The periodic tables Compare this to an order were incomplete and some using atomic weights. elements were placed in inappropriate groups if the Students can sketch how strict order of atomic Mendeleev came up with a weights was followed. solution for the organisation of the periodic table. Mendeleev overcame some of the problems by leaving Give students details of the gaps for elements that he reactions of some elements, thought had not been then ask them to predict discovered and in some what the reactions of places changed the order different elements might be. based on atomic weights. WS1.1 Elements with properties predicted by Mendeleev were discovered and filled the gaps. Knowledge of isotopes made it possible to
electrons in their outer shell (outer electrons) and this gives them similar chemical properties. 5.1.2.2 Before the discovery of protons, neutrons and electrons scientists attempted to classify the elements by arranging them in order of their atomic weights. The periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed. Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered and in some places changed the order based on atomic weights. Elements with properties predicted by Mendeleev were discovered and filled the gaps. Knowledge of isotopes made it possible to Describe steps in the development of the periodic table. Describe and explain how testing a prediction can support or refute a new scientific idea. 0.5 Put a timeline of the steps that Mendeleev went through into the correct order. Give students cards with the properties and atomic weights of the elements Mendeleev knew about. Ask them to place the cards into a order would classify the properties. Compare this to an order using atomic weights. Students can sketch how Mendeleev came up with a solution for the organisation of the periodic table. Give students details of the reactions of some elements, then ask them to predict what the reactions of different elements might be. WS1.1 or (interactive) University of Nottingham –