AQA GCSE Chemistry Unit 3 - The Early Periodic Table C3.1.1

Newlands spotted a pattern where properties of elements seemed to repeat themselves every eighth element. He proposed this as the law of octaves. 

Mendeleev later devised a periodic table and left gaps for undiscovered elements. He later made predictions for the properties of the elements which were, at the time, undiscovered.

When Newlands made his proposition, around half of the elements we know now were known, he wasn't aware of this as some of the elements had to 'share' spaces on the octave. Newlands used atomic mass to order the elements, he discovered the law of octaves when the elements were ordered this way, the properties tended to repeat themselves every eighth element. There were many inconsistancies in Newlands' ideas about similar properties so they weren't as quickly accepted, his…