![]() ![]() To make iodine line up with chlorine and bromine in his table, Mendeleev swapped the positions of iodine and tellurium. However, iodine has similar chemical properties to chlorine and bromine. So iodine should be placed before tellurium in Mendeleev's periodic table. ![]() Iodine has a lower atomic weight than tellurium. Its properties were found to be similar to the predicted ones and confirmed Mendeleev's periodic table. Another scientist later discovered the missing element, germanium. For example, Mendeleev predicted the existence of 'eka-silicon', which would fit into a gap below silicon. By looking at the properties of the elements next to a gap, he could also predict the properties of these undiscovered elements. Mendeleev left gaps in his table for elements not known at the time. However, from their atomic weights, some pairs of elements next to each other were in the wrong order. showed elements with similar chemical properties lined up in groups. ![]() He also took into account the properties of the elements and their compounds. In it, he arranged the elements in order of increasing atomic weights. He published his first periodic table of the elements in 1869. He wrote chemistry books and was looking for ways to organise the known elements. Dmitri Mendeleevĭmitri Mendeleev was a Russian chemist. Also, some elements were placed in groups with elements that were not similar to them. Įarly periodic tables were incomplete, since many elements were unknown. The atomic weight of an element is equivalent to what we now call its relative atomic mass. Also able to play as a wing-back, he has already built a reputation as a creative, dangerous attacker with an incredible burst of pace and composure on the ball. Mendeleev's periodic table Early attempts to classify elementsīefore discovering protons, neutrons and electrons, scientists tried to classify the elements by arranging them in order of their atomic weights. A powerful and direct winger, Timi (as he is known) made the step up to under-18 football last season, in his first year at the club. ![]()
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