Mendeleev left gaps in his Periodic Table.
Why did he leave these gaps?
He predicted that undiscovered elements would fill them.
He needed them to keep elements in atomic number order.
He wanted every period to contain exactly eight elements.
Some elements had isotopes with different atomic masses.
64 exam-style questions on OCR GCSE Chemistry 2.2 Bonding, covering 2.2.1 Metals, non-metals and the Periodic Table, 2.2.2 Types of chemical bonding and dot and cross diagrams, 2.2.3 Limitations of bonding models, and 2.2.4 Reactivity, atomic number and the modern Periodic Table. Each one has a worked solution and a mark scheme showing where the marks go.