<P> Group 3 is a group of elements in the periodic table . This group, like other d - block groups, should contain four elements, but it is not agreed what elements belong in the group . Scandium (Sc) and yttrium (Y) are always included, but the other two spaces are usually occupied by lanthanum (La) and actinium (Ac), or by lutetium (Lu) and lawrencium (Lr); less frequently, it is considered the group should be expanded to 32 elements (with all the lanthanides and actinides included) or contracted to contain only scandium and yttrium . When the group is understood to contain all of the lanthanides, its trivial name is the rare - earth metals . </P> <P> Three group 3 elements occur naturally, scandium, yttrium, and either lanthanum or lutetium . Lanthanum continues the trend started by two lighter members in general chemical behavior, while lutetium behaves more similarly to yttrium . While the choice of lutetium would be in accordance with the trend for period 6 transition metals to behave more similarly to their upper periodic table neighbors, the choice of lanthanum is in accordance with the trends in the s - block, which the group 3 elements are chemically more similar to . They all are silvery - white metals under standard conditions . The fourth element, either actinium or lawrencium, has only radioactive isotopes . Actinium, which occurs only in trace amounts, continues the trend in chemical behavior for metals that form tripositive ions with a noble gas configuration; synthetic lawrencium is calculated and partially shown to be more similar to lutetium and yttrium . So far, no experiments have been conducted to synthesize any element that could be the next group 3 element . Unbiunium (Ubu), which could be considered a group 3 element if preceded by lanthanum and actinium, might be synthesized in the near future, it being only three spaces away from the current heaviest element known, oganesson . </P> <P> In 1787, Swedish part - time chemist Carl Axel Arrhenius found a heavy black rock near the Swedish village of Ytterby, Sweden (part of the Stockholm Archipelago). Thinking that it was an unknown mineral containing the newly discovered element tungsten, he named it ytterbite . Finnish scientist Johan Gadolin identified a new oxide or "earth" in Arrhenius' sample in 1789, and published his completed analysis in 1794; in 1797, the new oxide was named yttria . In the decades after French scientist Antoine Lavoisier developed the first modern definition of chemical elements, it was believed that earths could be reduced to their elements, meaning that the discovery of a new earth was equivalent to the discovery of the element within, which in this case would have been yttrium . Until the early 1920s, the chemical symbol "Yt" was used for the element, after which "Y" came into common use . Yttrium metal was first isolated in 1828 when Friedrich Wöhler heated anhydrous yttrium (III) chloride with potassium to form metallic yttrium and potassium chloride . </P> <P> In 1869, Russian chemist Dmitri Mendeleev published his periodic table, which had empty spaces for elements directly above and under yttrium . Mendeleev made several predictions on the upper neighbor of yttrium, which he called eka - boron . Swedish chemist Lars Fredrik Nilson and his team discovered the missing element in the minerals euxenite and gadolinite and prepared 2 grams of scandium (III) oxide of high purity . He named it scandium, from the Latin Scandia meaning "Scandinavia". Chemical experiments on the element proved that Mendeleev's suggestions were correct; along with discovery and characterization of gallium and germanium this proved the correctness of the whole periodic table and periodic law . Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized the correspondence and notified Mendeleev . Metallic scandium was produced for the first time in 1937 by electrolysis of a eutectic mixture, at 700--800 ° C, of potassium, lithium, and scandium chlorides . </P>

Which is the longest group in periodic table