Question 2256
Which element trio forms a Dobereiner triad with atomic weights approximately 40, 88, and 137?
Question 2257
Which element trio forms a Dobereiner triad with atomic weights approximately 35.5, 80, and 127?
Question 2258
Which element trio forms a Dobereiner triad with atomic weights approximately 7, 23, and 39?
Question 2259
What common principle did Mendeleev and Meyer propose independently in 1869?
Question 2260
Which French geologist created an early periodic arrangement by plotting elements on a cylinder?