Topic 1b- Development of the periodic table (Paper 1 + 2)
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Who rediscovered the idea of elements in the early 1800s?
John Dalton.
Who built on Dalton’s ideas and what did they do?
Newlands created a table with “octaves.” He noticed the properties of every eighth element seemed similar, so his table had ascending order of mass in rows of eight.
Who was Mendeleev and what was different about his table?
He left gaps for undiscovered elements and made predictions about their properties. He reordered some of the elements because he believed they had been measured incorrectly.
What are three important differences between Mendeleev’s table and the modern periodic table?
• Modern periodic table is ordered using atomic number, Mendeleev used atomic mass. • Modern periodic table contains many more elements than Mendeleev’s. • No gaps in modern periodic table.