isolated elements

Jennifer, Alex, Aldric, I dont know

What have scientist known science they have been able to isolate pure elements

Some elements have very similar physical and physical properties.

what are common physical properties of lithium, sodium, and potassium?

silvery-grey metals, soft enough to cut

what property of elements is relatively easy to determine?

atomic mass

what other name is used to describe atomic mass?

atomic weight

what did scientist call groups of 3 similar elements?

triads

what seemed significant about the average atomic mass of similar elements in a triad?

similar physical and chemical properties seemed to show that these elements were related on a deeper level.