• Newlands

first to arrange the elements into a periodic table with increasing order of atomic masses.

every eight elements had similar properties and this is the “law of octaves”.

• Mendeleev (1860’s)

created element cards

sorted elements by how they reacted and then sorted them from lightest to heaviest

created a basic periodic table that left gaps for undiscovered elements

• Ramsey (1894’s)

did not know there were shells because electrons had not yet been discovered

discovered Noble Gases

• Moseley

discovered atomic numbers (from 20+ they were not accurate)

Silicon, Germanium, and Arsenic are the main metalloids