development of the periodic table

Question 1

why was the periodic table needed?

Answer 1

organisation

Question 2

eventually what was considered the most important factor to organising the elements?

Answer 2

atomic number

Question 3

how did John Dalton order the elements?

Answer 3

• used symbols
• arranged in order of the relative atomic mass numbers
▪︎ developed atomic theory

Question 4

how did John Newlands order the elements?

Answer 4

• arranged by increasing atomic mass
• rows of elements with similar properties but couldn’t get it all to match up
▪︎ laws of octaves

Question 5

how did Dmitri Mendeleev order the elements?

Answer 5

• first: arranged by atomic masses
• then: groups of elements with similar properties
▪︎ left gaps in his table for missing elements which were later found