Other elements are not shiny, malleable, or ductile, and are poor conductors of heat and electricity. For example, many elements appear shiny, are malleable and ductile, and conduct heat and electricity well. Many elements differ significantly in their chemical and physical properties, but some elements are similar in their behaviors. For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are usually written below the main body of the table. Groups are labeled at the top of each column. The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups. Each box represents an element and contains its atomic number, symbol, average atomic mass, and (sometimes) name. A modern periodic table arranges the elements in increasing order of their atomic numbers, and it groups atoms with similar properties in the same vertical column. The modern statement of this relationship, the periodic law, states the following: the properties of the elements are periodic functions of their atomic numbers. Although Mendeleev and Meyer had a long dispute over priority, Mendeleev’s contributions to the development of the periodic table are now more widely recognized.īy the twentieth century, it became apparent that the periodic relationship involved atomic numbers rather than atomic masses. The discoveries of gallium (1875) and germanium (1886) provided significant support for Mendeleev’s work. However, Mendeleev went one step further than Meyer he used his table to predict the existence of elements that would have properties similar to aluminum and silicon but were not yet known. Both published tables with the elements arranged according to increasing atomic mass. Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) also exhibit similar properties to each other, but these properties are drastically different from those of any of the elements above.ĭimitri Mendeleev in Russia (1869) and Lothar Meyer in Germany (1870) independently recognized a periodic relationship among the properties of the elements known at that time.

Additionally, Li, Na, and K form compounds with oxygen in a ratio of two of their atoms to one oxygen atom, whereas Ca, Sr, and Ba form compounds with one of their atoms to one oxygen atom. For example, Li, Na, and K are much more reactive than Ca, Sr, and Ba. However, the specific properties of these two groupings are notably different from each other. A second grouping includes calcium (Ca), strontium (Sr), and barium (Ba), which also are shiny, good conductors of heat and electricity, and have chemical properties in common. All of these elements are shiny, conduct heat and electricity well, and have similar chemical properties. One such grouping includes lithium (Li), sodium (Na), and potassium (K). As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors.

Chemistry group names periodic table