The atomic number was discovered by Henry Moseley in 1913.
Henry Moseley's discovery was a major breakthrough in understanding the structure of atoms. Before his work, elements were primarily ordered based on their atomic weight. However, this system had some inconsistencies. Moseley's work, which involved the study of x-ray spectra, revolutionized how we understand the periodic table.
Moseley's Experiment and Findings
Moseley's experiments involved bombarding different elements with electrons and analyzing the resulting x-ray spectra. He found a direct, linear relationship between the frequency of certain lines in the x-ray spectrum and the position of the element in the periodic table. His findings are summarized below:
- He discovered that certain lines in the x-ray spectrum of elements shift by a consistent amount with each increase in the atomic number by one.
- This established the atomic number as a more fundamental property than atomic weight.
- This discovery allowed for a more logical and accurate arrangement of the periodic table.
Moseley's work led to the modern definition of atomic number as the number of protons in the nucleus of an atom. This foundational discovery played a crucial role in the development of quantum mechanics and our understanding of the structure of the atom.
| Key Figure | Year of Discovery | Key Finding |
|---|---|---|
| Henry Moseley | 1913 | Established the atomic number by studying x-ray spectra. |
In summary, Henry Moseley's investigation of x-ray spectra was instrumental in identifying the atomic number, revealing a more accurate representation of element organization than atomic weight.
