Friedrich Wöhler (July 31, 1800 - September 23, 1882) was a Germanchemist, -known for his synthesis of urea, but also the first to isolate several of the elements. In 1828 Wöhler proved by his preparation of urea from inorganic materials that organic substances do not have to come from biological sources, disproving the doctrine of vitalism.
Copper(II) sulfate is one of the most familiar compounds of copper. It also occurs naturally as the mineral chalcanthite. It is commonly used in schools for growing crystals. The pictured substance is the pentahydrate form.
Chemist Otto Hahn and physicist Lise Meitner collaborated on radiochemistry for thirty years in Berlin. In 1918 they discovered the first long-lived isotope of protactinium, and they are also both credited for the 1938 discovery of nuclear fission. Hahn went on to win the 1944 Nobel Prize for Chemistry alone, but Meitner is regarded as having provided the explanation for Hahn's observations. Meitner had fled Nazi Germany in 1938, preventing joint publication. She is now commemorated in element no. 109, meitnerium.
Gas chromatography is an important type of chromatography used in chemical analysis. A volatile substance or mixture is injected and carried down a column (the coil shown) to a detector, which records the amount and the time on the column for each component. An oven (shown here with the door open) maintains the column at a desired temperature.
Activation energy is the energy that must be overcome for a chemical reaction to occur. Here, the sparks generated by striking steel against a flint provide the activation energy to initiate combustion in a Bunsen burner. The blue flame will sustain itself after the sparks are extinguished because the continued combustion of the flame is now energetically favorable.
Aerogel is a low-density solid-state material derived from gel in which the liquid component of the gel has been replaced with gas. The result is an extremely low density solid with several remarkable properties, most notably its effectiveness as a thermal insulator. It is also very strong structurally, able to hold over 2000 times its own weight. Its impressive load bearing abilities are due to the dendritic microstructure. In the image, a 2.5kg brick is supported by a piece of aerogel weighing only 2.38 grams.
A bismuthcrystal covered with an iridescentoxide surface. Bismuth is a post-transition metal with the atomic number 83. It is generally considered to be the last naturally occurring stable, non-radioactive element on the periodic table, although it is actually slightly radioactive. Bismuth compounds are used in cosmetics, medicines, and in medical procedures. As the toxicity of lead has become more apparent in recent years, alloy uses for bismuth metal as a replacement for lead have become an increasing part of bismuth's commercial importance.