Mendeleev left gaps in his periodic table because the properties of known elements predicted other, as-yet-undiscovered, elements in these locations. As Mendeleev organized his periodic table, he recognized that these gaps would be filled as future scientists identified new elements.Continue Reading
Mendeleev put together the periodic table on the basis of known properties about atoms, specifically the atomic mass, equivalent mass and valency. This method revealed repetitive, or periodic, patterns among the elements that suggested an inherent organization. In some cases, the measured atomic mass of an atom conflicted with its predicted position in Mendeleev's periodic table. In these situations, Mendeleev correctly assumed that the measurement was wrong, and he successfully estimated the correct atomic mass.
Similarly, Mendeleev predicted the properties of the elements that would fill the blank spaces in his periodic table. For example, he anticipated the discovery of gallium (which Mendeleev called eka-aluminum) as well as several characteristics of this element. He quite accurately estimated features such as the atomic mass, density, valency and even the method of discovery of gallium. His predictions were similarly impressive in predicting the discovery of scandium, germanium and other elements; however, his predictions were not uniformly accurate. In at least three cases, the gaps in his table did not lead to the discovery of a new element.Learn more about Atoms & Molecules
Many elements on the periodic table have names derived from Latin, including aluminum, calcium, cesium, chlorine, fluorine, gallium, iridium, radium, rubidium and scandium. Other element names are derived from languages such as Greek, Arabic and Anglo-Saxon. Some elements have been named for the cities in which they were discovered or after scientists.Full Answer >
The periodic table classifies chemical elements by their similarities and properties. Each square in the periodic table shows an element's atomic number, its symbol, its name and its atomic weight, which is the number of protons and neutrons the element has.Full Answer >
Periodic law, also known as Mendeleev's law, is the concept that the chemical and physical properties of elements are based on an element's atomic weight when arranged by increasing periodic atomic number. Periodic law was first developed in 1869 when Dimitri Mendeleev and Lothar Meyer each developed a periodic table on their own and noticed similarities in elements with comparable atomic masses. Both men organized the elements by their masses and noticed certain properties recur periodically.Full Answer >
The elements in the periodic table are organized by their atomic numbers, their electron configurations and the recurring properties found in them. Elements are arranged in blocks, with elements found in that block all containing consistent properties. For instance, all alkali metals are highly reactive, and all noble gases are inert, meaning they cannot react with other elements under normal conditions.Full Answer >