History of Chemistry (continued)

Humphy Davy discovered, between 1807 and 1808, as many other elements as sodium, potassium, calcium, and barium.

Later, other elements such as iodine, lithium, cadmium, selenium, silicon, aluminum, bromine, thorium, beryllium, vanadium were discovered.

Mosander, in 1839, discovered lanthanum. In 1843, the terbium and erbium. Through spectroscopy Bunsen discovered cesium and rubidium in 1860.

Bunsen discovered the elements cesium and rubidium

Thallium and indium were also identified by spectroscopy, as were helium and boron.

In 1871, Russian Dmitri Mendeleiev foresaw some elements that would complete the periodic table. From 1875, some chemists proved and existence of these elements, confirming what Mendeleev had said.

The elements discovered were: gallium, thulium, ytterbium, scandium, gadolinium, holmium, samarium.

Dmitri Mendeleiev

In 1885 and 1886, praseodymium, neodymium, dysprosium and germanium were discovered.

Argon inert gas was discovered in 1894 by Sir Willian Ramsay and was classified as a noble gas. In 1898 Ramsay also isolated neon, krypton and xenon.

Neon gas, used in bright signs

At this same time, the Curie couple discovered elements with radioactive properties, such as radio, polonium and actinium.

Curie couple discovered radioactive elements

Radon, lutetium, protactinium, hafnium and rhenium were later discovered by other chemists.

By 1925, almost all stable elements of the earth's crust were already in the periodic table.

Synthetic elements began to be produced. They are unstable. Before that, they discovered technetium and francium.

They are artificial elements: neptune, plutonium, curium, americium, promethium, berkelium, californium, einstenium, fermium, mendelevius, nobelium, laurentius, ruterphorium, dubium, seaborium, borium, hassium, meentium, darmstadium, roentgenium.