How was the atomic number discovered?
Henry Moseley discovered the atomic number.
he was able to show that the atomic number is equal to the protons present in the atom.
that means the atomic number is equal to the positive charge of the atom...
how he related the atomic number to the available number of protons ?
Moseley measured the frequency of the X-rays given off by different elements. Each element gave a different frequency and he found that this frequency was mathematically related to the position of the element in the Periodic Table – he could actually measure atomic number.
(Moseley plotted the square root of the X-ray frequency against atomic number)