Question

who was the first chemist to organize elements by atomic number?
johann wolfgang döbereiner
antoine lavoisier
henry moseley
john newlands

Explanation:

To determine the first chemist to organize elements by atomic number, we analyze each option:

• Johann Wolfgang Döbereiner grouped elements into triads based on similar properties, not atomic number.
• Antoine Lavoisier is known for work on chemical reactions and element classification (like defining elements), not organizing by atomic number.
• Henry Moseley established that the atomic number (number of protons) is the fundamental property for element organization, and he was the first to organize elements by atomic number.
• John Newlands arranged elements by atomic mass in octaves, not by atomic number.

Answer:

C. Henry Moseley