C3 1 The Early Periodic Table

Question 1

Why was the periodic table developed?

Answer 1

To classify elements. It arranges them in a pattern in which similar elements are grouped together

Question 2

What did John Dalton do with the elements?

Answer 2

John Dalton arranged the elements in order of their masses which had been measured in various chemical reactions. In 1808, he published a table of elements in his book ‘A New System of Chemical Philosophy’

Question 3

What did John Newlands do with the elements?

Answer 3

In 1864, Newlands built on Dalton’s ideas with his law of octaves. Newlands arranged the known elements in order of mass. He noticed that the properties of every eighth element seemed similar
However, he assumed that all the elements had been found so his table only really worked for the known elements up to calcium

Question 4

What did Mendeleev do with the elements?

Answer 4

In 1869, Russian chemist Mendeleev cracked the problem. Mendeleev arranged the 50 elements that had been identified into a table. He placed them in order of atomic weights. Then he arranged them so that a periodic pattern in their properties could be seen
He left gaps for undiscovered elements so he could predict their properties

Question 5

What does the atomic number determine?

Answer 5

Its position in the periodic table

Question 6

What does the electron number determine?

Answer 6

In the outermost shell, it determines its chemical properties

Question 7

What does the group number show?

Answer 7

It equals the number of electrons in the outermost shell

Question 8

Trends of reactivity going down a group:

Answer 8

• The distance between the outermost electrons and the nucleus
• The number of occupied inner shells (energy levels) in the atoms