what do the columns and rows on the periodic table represent
Periodic table The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties. This adopted ordering shows periodic trends, such as elements with similar behaviour in the same column. It also shows four rectangular blocks with some approximately similar chemical properties. Generally, within one row (period) the elements are metals on the left, and non-metals on the right. Table rows are called periods and columns are called groups. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are halogens; and group 18 are noble gases.
History of the periodic table The history of the periodic table reflects over a century of growth in the understanding of chemical properties. The most important event in its history occurred in 1869, when the table was published by Dmitri Mendeleev,[2] who built upon earlier discoveries by scientists such as Antoine-Laurent de Lavoisier and John Newlands, but who is nevertheless generally given sole credit for its development.