In 1789, a scientist named Antoine Lavoisier from France tried to organize different things called elements into two groups: one with metals and the other with nonmetals.. Forty years later, German physicist Johann Wolfang Dobereiner observed similarities in physical and chemical properties of these elements. He arranged them in groups of three in increasing order according to their atomic weight and called them triads, observing that some properties of the middle element, such as atomic weight and density. In 1860 Germany concluded that hydrogen would be assigned the atomic weight of 1 and the atomic weight of other elements would be decided by comparison with hydrogen.British chemist John Newlands was the first to arrange the elements into a periodic table with increasing order according to their atomic masses. He noticed that every eighth element acted alike, and he named this the "law of octaves." He put the elements in eight groups without any empty spaces for elements we didn't know about yet.. In 1869, Russian chemist Dmitri Mendeleev created the framework that became the modern periodic table,leaving gaps for undiscovered elements.
Mendeleev guessed what some new elements might be like, even though they hadn't been found yet. He called one of them "eka-aluminium" because it acted a lot like aluminium.
