Why were early periodic tables ordered by atomic weight rather than atomic number?
Protons and electrons were not yet known, so atomic number could not be used.
To place each element with others having similar properties.
Atomic weight is an average of isotope masses.
The arrangement also had to match their chemical properties.
Flashcards for AQA GCSE Chemistry 1.2.2 Development of the periodic table, covering the key terms, definitions and equations you need to recall for Paper 1 and Paper 2. 20 cards, matched to the AQA GCSE Chemistry (8462) specification. Recall questions account for roughly 40% of marks at GCSE Chemistry, so these target the marks you can secure before the paper starts.
