Labels:book | daily | earth | plant | poster | reckoner | road | sky | stairs | tree | windowpane OCR: "HE PERIODIC TABLE provides instant information about all the elements and arranges them in such way that those with similar properties are grouped together. But how did scientists work out the table? In 1829 the German chemist Johann Dobereiner (1780 1849) noticed that some elements could be arranged in groups of three because all three members of each group beh aved similarly Dobereiner called these groups triads Later, the English chemist John Newlands (1837 98) arranged elements in groups of eight which he called octaves. but his work was largely ignored b the scientific community SIMILAR PROPERTIES By this time, scientists were aware that different elements have different atomic weights (the number of protons and neutrons in each atom o an element; now called atomic mass). The brea ak ...
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