3.1- Periodicity

Question 1

What did Aristotle propose about atoms

Answer 1

354-322BC- Aristotle believed the world was made up of 4 elements, water earth fire and air. We now call these the states of matter- solid, liquid gas and plasma

Question 2

1789- Antoine Laurent de Lavoisier

Answer 2

Compiled the first extensive list of elements. Also included some compounds/ mixtures, as well as terms like light and caloric

Question 3

1828- Jöns Jakob Berzelius

Answer 3

Published table of atomic weights and introduced letter based symbols for elements instead of signs

Question 4

Johann Wolfgang Döbereiner

Answer 4

Noticed that certain groups of 3 elements ordered by atomic weight would have a middle element with the average weight and average of the properties of the other 2
E.g Calcium Strontiym and Barium

Question 5

John Newlands

Answer 5

Arranged periodic table by relative atomic mass (atomic weight). Also introduced the idea of the law of octaves- noticed that every 8th element has similar properties

Question 6

Dmitri Mendeleev

Answer 6

Arranged elements in order of atomic weight. Arranged elements with similar properties in vertical columns that also corresponded to their valencies . left gaps for missing elements and predicted their properties.

Question 7

What is periodicity

Answer 7

Describes the repeating pattern seen within periods and groups of