A dimer (/ˈdaɪmər/) (di-, "two" + -mer, "parts") is an oligomer consisting of two structurally similar monomers joined by bonds that can be either strong or weak, covalent or intermolecular. The term homodimer is used when the two molecules are identical (e.g. A-A) and heterodimer when they are not (e.g. A-B). The reverse of dimerisation is often called dissociation.

Noncovalent dimers

Carboxylic acids form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen when anhydrous. For example, acetic acid forms a dimer in the gas phase, where the monomer units are held together by hydrogen bonds. Under special conditions, most OH-containing molecules form dimers, e.g. the water dimer.

Borane ("BH₃") occurs as the dimer diborane (B₂H₆), due to the high Lewis acidity of the boron center.

Excimers and exciplexes are excited structures with a short lifetime. For example, noble gases do not form stable dimers, but do form the excimers Ar₂*, Kr₂* and Xe₂* under high pressure and electrical stimulation.

In the history of science, the etymology of the word chemistry is debatable. It is agreed that the word derives from the word alchemy, which is a European one, derived from the Arabic al-kīmīā (الكيمياء). The Arabic term is derived from the Greek χημία or χημεία. However, the ultimate origin of the root word, chem, is uncertain.

According to the Oxford English Dictionary, the majority theory is that al-kīmīā is derived from χημία, which is derived from the ancient Egyptian name of Egypt (khem, khame, or khmi, meaning "black earth", contrasting with the surrounding desert.) Therefore, alchemy is the "Egyptian art". However, it is also possible that al-kīmīā derived from χημεία, meaning "cast together".

Traditionally, the science of alchemy was once considered to have sprung from great Egyptian figure named by the Greeks "Hermes Trismegistus" (the "thrice-great" Hermes, celebrated as priest, king, and scholar), who is thought to have been the founder of the art. Reputed to have lived about 1900 BC, he was highly celebrated for his wisdom and skill in the operations of nature. In 1614 Isaac Casaubon demonstrated that the works attributed to Hermes – the so-called "Hermetic corpus" – were actually written pseudonymously during the first three centuries of the Common Era.

"Chemistry" is the sixth episode of the American television series, Smash. The episode aired on March 12, 2012.

Plot

Ivy (Megan Hilty) comes down with laryngitis, Julia (Debra Messing) keeps bumping into Michael (guest star Will Chase), Eileen (Anjelica Huston) and Ellis (Jamie Cepero) talk at a bar, Karen (Katharine McPhee) performs for a bar mitzvah.

Production

Recurring guest stars include Will Chase as actor Michael Swift.

One of the cover songs already announced is "Shake It Out" by Florence + the Machine performed by Katharine McPhee. Additionally, "History is Made at Night" performed by Megan Hilty, Chase and the cast of Marilyn will make a reappearance in this episode, having first been heard in the episode "The Cost of Art", and Hilty's solo version of "Let Me Be Your Star" first heard in the pilot will be heard in the episode. Also, Hilty's version of Jessie J's "Who You Are" was also in the episode. Only "History is Made at Night" was made available as a single on iTunes.

"Chemistry" is a song by the alternative rock band Semisonic. It was their first single on their 2001 album, All About Chemistry. It reached 39 on Billboard's Modern Rock Tracks and 35 on the UK Singles Chart. The song was featured in the film 40 Days and 40 Nights and in the TV series Men in Trees and Roswell.

Music video

The music video for this song was filmed in 2000 in a house in Silver Lake, California. The video was directed by Liz Friedlander. It features the journey of a small silver ball which, at one stage, passes through a Rube Goldberg machine, and includes a series of domestic disasters.

References

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