Chemistry- Development of the periodic table:

Newlands’ octaves

Part of Newlands' table

An English scientist called John Newlands put forward his Law of Octaves in 1864. He arranged all the elements known at the time into a table in order of relative atomic mass.

When he did this, he found a pattern among the early elements. The pattern showed that each element was similar to the element eight places ahead of it.

For example, starting at Li (lithium), Be (beryllium) is the second element, B (boron) is the third and Na (sodium) is the eighth element. He then put the similar elements into vertical columns, known as groups.

Regular repeats

Newlands' table showed a repeating or periodic pattern of properties, but this pattern eventually broke down.

By ordering strictly according to atomic mass, Newlands was forced to put some elements into groups which did not match their chemical properties. For example, he put iron (Fe), which is a metal, in the same group as oxygen (O) and sulfur (S), which are two non-metals.

As a result, his table was not accepted by other scientists.

Mendeleev's periodic table

In 1869, just five years after John Newlands put forward his Law of Octaves, a Russian chemist called Dmitri Mendeleev published a periodic table.

Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made…