dmitri mendeleev was the first chemist to start grouping elements based on their properties.
who was the first chemist to start grouping elements based on their properties?
dmitri mendeleev
in 1789, antoine lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths. chemists spent the following century searching for a more precise classification scheme. in 1829, johann wolfgang döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third. this became known as the law of triads. german chemist leopold gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. jean-baptiste dumas published work in 1857 describing relationships between various groups of metals. although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all. in 1857, german chemist august kekulé observed that carbon often has four other atoms bonded to it. methane, for example, has one carbon atom and four hydrogen atoms. this concept eventually became known as valency, where different elements bond with different numbers of atoms.
periodic table
section::::most significant digit radix sorts.:recursion.





























a recursively subdividing msd radix sort algorithm works as follows:





























bullet::::1. take the most significant digit of each key.





























bullet::::2. sort the list of elements based on that digit, grouping elements with the same digit into one bucket.





























bullet::::3. recursively sort each bucket, starting with the next digit to the right.





























bullet::::4. concatenate the buckets together in order.





























section::::most significant digit radix sorts.:recursive forward radix sort example.





























sort the list:





























br170, 045, 075, 090, 002, 024, 802, 066
radix sort