Beginning of Essay
T3 IBS Chemistry Ms. Redman The idea behind the "atom" goes back to the Ancient Greek society, where scientists believed that all matter was made of smaller, more fundamental particles called elements. They called these particles atoms, meaning "not divisible." T ....

Middle of Essay
.... states that elements show a regular pattern ("periodicity") when they are arranged according to their atomic masses), published his first attempt to classify the known elements. His name was Mendeleyev, and he was a renowned teacher. Because no good textbook in chemistry was available at the time, he wrote the two-volume Principles of Chemistry (1868-1870), which later became a classic. During the writing of this book, Mendeleyev tried to classify the elements according to their chemical properties. In 1871 he published an improved version of the periodic table, in which he left gaps for elements that were not yet known. His chart and theo ....