Periodic Table

Question 1

Robert boyle

Answer 1

First accurate description of an element

an element is a substance that cannot be split into simpler substances by chemical means

Question 2

Humphry Davy

Answer 2

Studied the effect of passing electricity through different substances

Isolated the elements potassium sodium and calcium through electrolysis

Question 3

Dobereiner’s triads

Answer 3

Triad is a group of elements with similar chemical properties in which the atomic weight of the middle element is approximately halfway between the other two

Question 4

Newland’s octaves

Answer 4

When arranged by atomic weight the properties of elements seemed to be repeated every eight element

this is called the law of octaves

Question 5

Mandelev’s periodic law

Answer 5

When elements are arranged according to atomic weight their properties repeat periodically

left gaps

Question 6

Henry moseley

Answer 6

Atomic number (using x-ray analysis)

Rearranged mandeleev’s table according to atomic number.

Question 7

The differences between mandeleev’s periodic table and the modern periodic table

Answer 7

Elements arranged from atomic weight to atomic number

From gaps for undiscovered elements to no gaps

Does not have group 8 to having a group 8

transition metals were not in a separate block but now they are

Question 8

Relative atomic mass

Answer 8

Ar

Is the average mass of an atom negative relative to 1/12 of the mass of an atom of carbon-12

Formula= (abundancexmass + abundancexmass ) \ 100