A Pattern of properties appeared when he arranged the elements in order of increasing Atomic Mass
Increasing atomic mass
Demitri Mendeleev discovered a pattern to the periodic table in 1869.
He did order it in the periodic table, but i think what your looking for is that he arranged it in order of increasing Atomic mass
By placing the elements in order of their Atomic Mass then grouping them based on similar chemical properties, Mendeleev recognized that there were gaps in the pattern he made where elements should be. He predicted there were some elements yet to be discovered and predicted their chemical properties. The elements he predicted were later discovered and named germanium, gallium, and scandium.
He had to sing a song about the elements!
Mendeleev used the analogy of playing the card game of solitaire to help him organize the known elements into a periodic table. The suits of the cards were analogous to the groups of the elements and the numeric values of the cards were analogous to the values of atomic weights.
Meneleev arranged the elements
He is credited as being the creator of the first version of the periodic table of elements. Using the table, he predicted the properties of elements yet to be discovered.
He could predict other elements because there was an obvious gap, but he couldn't predict the noble gases because he didn't realize that there was going to be an 18th group since none of them were yet discovered. When he first started organizing the periodic table, the pattern still made sense even without the noble gases.
A Pattern of properties appeared when he arranged the elements in order of increasing Atomic Mass
Mendeleev arranged the elements are arranged in order of increasing atomic masses. He founded that properties of elements are periodic when arranged in this pattern.
It is The Periodic Table of Elements
mendeleev arranged elements according to atomic mass. He was able to observe periodicity when arranged in this pattern.