question: HeH+ How do scientists know it's the earliest molecule? Does the plus at the end mean it's an ionic compound? Why is that significant?
comment: The plus means it’s charged thus it has more protons than electrons, unsure of the earliest molecule part.
passages: After the original synthesis in 2010, Dawn Shaughnessy of LLNL and Oganessian declared that naming was a sensitive question, and it was avoided as far as possible. However, Hamilton declared that year, "I was crucial in getting the group together and in getting the Bk target essential for the discovery. As a result of that, I’m going to get to name the element. I can’t tell you the name, but it will bring distinction to the region." (Hamilton teaches at Vanderbilt University in Nashville, Tennessee, U.S.)
   Being a sesquiterpenoid, JH chemical structure differs significantly from the structure of other animal hormones. Some JH analogs have been found in conifers.
  
  Section::::Control of development.
   The general term protoporphyrin refers to porphine derivatives that have the outer hydrogen atoms in the four pyrrole rings replaced by four methyl groups (M), two vinyl groups (V), and two propionic acid groups (P). The Roman numeral "IX" indicates that these chains occur in the circular order MV-MV-MP-PM around the outer cycle. (The numbering of the variants is traditional and not entirely systematic.)
  
  Section::::Natural occurrence.
   1H
  
  1H or 1-H may refer to:
  
  BULLET::::- 1H, a number of chemical compounds with one hydrogen atom
  
  BULLET::::- 1H, a grouping within an Astronomical catalog
  
  BULLET::::- 1H 1617-155, a designation for the Scorpius X-1 X-ray source
  
  BULLET::::- 1H 1908+047, a designation for the SS 433 star system
  
  BULLET::::- 1H, an SES satellite launched June 16, 1999
  
  BULLET::::- 1H, a model of Nissan H engine
  
  BULLET::::- 1H NMR, a type of Proton NMR
  
  BULLET::::- 1 H. Cas, a variant notation for AR Cassiopeiae
  
  BULLET::::- UH-1H, a type of Bell UH-1 Iroquois
  
  BULLET::::- Campath-1H, a brand of Alemtuzumab
   2H
  
  2H or 2-H may refer to:
  
  BULLET::::- Deuterium, or 2H, an isotope of Hydrogen
  
  BULLET::::- 2nd half of a fiscal year
  
  BULLET::::- 2H lead, a type of lead in a pencil
  
  BULLET::::- 2H, a type of Toyota H engine
  
  BULLET::::- 2H, a type of Volkswagen EA827 engine
  
  BULLET::::- Douglas O-2H, a model of Douglas O-2
  
  BULLET::::- Chaparral 2H, one model of Chaparral Cars
  
  BULLET::::- Aptera 2h, a model in the Aptera 2 Series
  
  BULLET::::- SSH 2H (WA), alternate designation for Washington State Route 290
  
  BULLET::::- 2H, a designation for chemicals with two hydrogen molecules
   The idea of hydrogen in the nascent state having chemical properties different from those of molecular hydrogen was developed the mid-nineteenth century. Alexander Williamson repeatedly refers to nascent hydrogen in his textbook "Chemistry for Students", for example writing of the substitution reaction of carbon tetrachloride with hydrogen to form products such as chloroform and dichloromethane that the "hydrogen must for this purpose be in the nascent state, as free hydrogen does not produce the effect". Williamson also describes the use of nascent hydrogen in describing earlier work of Marcellin Berthelot. Franchot published a paper on the concept in 1896, which drew a strongly worded response from Tommasi who pointed to his own work that concluded "nascent hydrogen is nothing else than H + "x" calories".
   The fourth "classical" oxide, mellitic anhydride (CO), was apparently obtained by Liebig and Wöhler in 1830 in their study of mellite ("honeystone"), but was characterized only in 1913, by Meyer and Steiner.
  
  Brodie also discovered in 1859 a fifth compound called graphite oxide, consisting of carbon and oxygen in ratios varying between 2:1 and 3:1; but the nature and molecular structure of this substance remained unknown until a few years ago, when it was renamed graphene oxide and became a topic of research in nanotechnology.
   Spectrochemical series
  
  A spectrochemical series is a list of ligands ordered on ligand strength and a list of metal ions based on oxidation number, group and its identity. In crystal field theory, ligands modify the difference in energy between the d orbitals (Δ) called the ligand-field splitting parameter for ligands or the crystal-field splitting parameter, which is mainly reflected in differences in color of similar metal-ligand complexes.
  
  Section::::Spectrochemical series of ligands.
  
  The spectrochemical series was first proposed in 1938 based on the results of absorption spectra of cobalt complexes.
   However, keep in mind that "the spectrochemical series is essentially backwards from what it should be for a reasonable prediction based on the assumptions of crystal field theory." This deviation from crystal field theory highlights the weakness of crystal field theory's assumption of purely ionic bonds between metal and ligand.
   database, the first group comprises the structures, called hP3, tI12, st12, r8, I41/a, P41212, m32, m32*, t32, t32*, H-carbon and uni. Among them st12 carbon was proposed as far as 1987 in the work of R. Biswas et al.
   In Asimov's writings the endochronicity of thiotimoline is explained by the fact that in the thiotimoline molecule, there is at least one carbon atom such that, while two of the carbon's four chemical bonds lie in normal space and time, one of the bonds projects into the future and another into the past. Thiotimoline is derived from the bark of the (fictitious) shrub "Rosacea karlsbadensis rugo", and the thiotimoline molecule includes at least fourteen hydroxy groups, two amino groups, and one sulfonic acid group, and possibly one nitro compound group as well. The nature of the hydrocarbon nucleus is unknown, although it seems in part to be an aromatic hydrocarbon.
   The history of the structure of W(CH) illustrates an inherent difficulty in interpreting spectral data for new compounds: initial data may not provide reason to believe the structure deviates from a presumed geometry based on significant historical precedence, but there is always the possibility that the initial assignment will prove to be incorrect. Prior to 1989, there was no reason to suspect that ML compounds were anything but octahedral, yet new evidence and improved characterization methods suggested that perhaps there were exceptions to the rule, as evidenced by the case of W(CH). These discoveries helped to spawn re-evaluation of the theoretical considerations for ML geometries.
   Once a lead compound series has been established with sufficient target potency and selectivity and favourable drug-like properties, one or two compounds will then be proposed for drug development. The best of these is generally called the lead compound, while the other will be designated as the "backup".
  
  Section::::Nature as source.
  
  Traditionally many drugs and other chemicals with biological activity have been discovered by studying allelopathy – chemicals that organisms create that affect the activity of other organisms in the fight for survival.
   BULLET::::- Name this longest root chain using standard naming rules
  
  BULLET::::- Name each side chain by changing the suffix of the name of the silane from "-ane" to "-anyl", except for "silane" which becomes "silyl"
  
  BULLET::::- Number the root chain so that the sum of the numbers assigned to each side group will be as low as possible
  
  BULLET::::- Number and name the side chains before the name of the root chain
  
  The nomenclature parallels that of alkyl radicals.
   Lithium is one of the few elements synthesized in the Big Bang, making it a primordial element.
  
  Lithium is the 33rd most abundant element on earth, occurring in concentrations of between 20 and 70 ppm by weight, but due to its high reactivity it is only found naturally in compounds.
   Section::::Recognition site.
  
  As of the end of 2010, there were 5 crystal structures of "Bam"H I in the Protein Data Bank
  
  Section::::Two-metal Mechanism.
   Hexacoordinate phosphorus molecules involving nitrogen, oxygen, or sulfur ligands provide examples of Lewis acid-Lewis base hexacoordination. For the two similar complexes shown below, the length of the C-P bond increases with decreasing length of the N-P bond; the strength of the C-P bond decreases with increasing strength of the N-P Lewis acid-Lewis base interaction.
  
  Section::::Structure, reactivity, and kinetics.:Structure.:Pentacoordinated silicon.
  
  This trend is also generally true of pentacoordinated main-group elements with one or more lone-pair-containing ligand, including the oxygen-pentacoordinated silicon examples shown below.
   Since then many triple-, quadruple-, penta-, and hexadecker decker sandwich complexes have been described. The largest structurally characterized multidecker sandwich monomer is the hexadecker shown at lower right 
  
  An extensive family of multidecker sandwiches incorporating planar (RR'CBR") (diborolyl) ligands has also been prepared.
  
  Numerous multidecker sandwich compounds featuring hydrocarbon bridging rings have also been prepared, especially triple deckers. A versatile method involves the attachment of Cp*Ru to preformed sandwich complexes.
  
  Section::::Classes.:Linked sandwiches.
  
  Monomeric double-decker and multidecker sandwiches have been used as building blocks for extended systems, some of which exhibit electron delocalization between metal centers. 
   Some chemists treat the categories "d-block elements" and "transition metals" interchangeably, thereby including groups 3–12 among the transition metals. In this instance the group 12 elements are treated as a special case of transition metal in which the d electrons are not ordinarily involved in chemical bonding. The 2007 report of mercury(IV) fluoride (HgF), a compound in which mercury would use its d electrons for bonding, has prompted some commentators to suggest that mercury can be regarded as a transition metal. Other commentators, such as Jensen, have argued that the formation of a compound like HgF can occur only under highly abnormal conditions; indeed, its existence is currently disputed. As such, mercury could not be regarded as a transition metal by any reasonable interpretation of the ordinary meaning of the term.
   The seleke of TRH was first determined, and the hormone synthesized, by Roger Guillemin and Andrew V. Schally in 1969. Both parties insisted their labs determined the sequence first: Schally first suggested the possibility in 1966, but abandoned it after Guillemin proposed TRH was not actually a peptide. Guillemin's chemist began concurring with these results in 1969, as NIH threatened to cut off funding for the project, leading both parties to return to work on synthesis.
   BULLET::::1. The parent hydrocarbon chain has 23 carbons. It is called tricosa-.
  
  BULLET::::2. The functional groups with the highest precedence are the two ketone groups.
  
  BULLET::::1. The groups are on carbon atoms 3 and 9. As there are two, we write 3,9-dione.
   BULLET::::- the "main bridge" refers to a bridge that connects two bridgeheads of the main ring, where the main bridge of norbornane is its only bridge, the one atom connecting the two bridgehead atoms (indicated at right, above, by the arrows); and
  
  BULLET::::- "secondary bridge" refers to any other bridges in the ring system that are not the "main bridge" of the "main ring."
  
  Section::::Examples.
   JHEH is a membrane associated protein, and by photoaffinity labeling has been shown to be a 50 kDA protein in "Manduca sexta".
  
  It has been noted by several that properties of JHEH are similar to those of animal microsomal epoxide hydrolase. Sequence alignments showed that the exact catalytic triad of the animal enzyme (Asp-226, Glu-403 and His-430) is present in JHEH. In addition, the X-ray structure of "Bombyx mori" JHEH was recently determined.
  
  Section::::Post translational modification.
   Section::::History of discovery.
   In December 2015, the IUPAC/IUPAP Joint Working Party recognized the element's discovery and assigned the priority to the Dubna-Livermore collaboration of 2009–2010, giving them the right to suggest a permanent name for it. While they did not recognise the experiments synthesising Mc and Mc as persuasive due to the lack of a convincing identification of atomic number via cross-reactions, they recognised the Ts experiments as persuasive because its daughter Mc had been produced independently and found to exhibit the same properties.
  