The Periodic Puzzle in achieve3000
Based on the article, which of these is true?

Mendeleev helped John Newlands with his experiments.
Mendeleev arranged the elements by atomic number.
Highly reactive metals are on the left side of the periodic table.
Highly reactive metals are on the right side of the periodic table.

All Answers 1

Answered by GPT-5 mini AI
Highly reactive metals are on the left side of the periodic table.

(Alkali and alkaline-earth metals on the left are the most reactive. Mendeleev arranged elements by atomic mass, not atomic number, and he did not help John Newlands.)