Chemistry[edit]
- H2, the chemical formula for hydrogen gas (dihydrogen)
- Deuterium (Hydrogen-2, H-2, 2H), the isotope of hydrogen with one proton, one neutron, and one electron
H
or
D
, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one neutron, whereas the far more common protium has no neutrons in the nucleus. Deuterium has a natural abundance in Earth's oceans of about one atom in 6420 of hydrogen. Thus deuterium accounts for approximately 0.0156% (0.0312% by mass) of all the naturally occurring hydrogen in the oceans, while protium accounts for more than 99.98%. The abundance of deuterium changes slightly from one kind of natural water to another (see Vienna Standard Mean Ocean Water).
A hydrogen atom is an atom of the chemical element hydrogen. The electricallyneutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogenconstitutes about 75% of the baryonic mass of the universe.[1]
In everyday life on Earth, isolated hydrogen atoms (called "atomic hydrogen") are extremely rare. Instead, a hydrogen atom tends to combine with other atoms in compounds, or with another hydrogen atom to form ordinary (diatomic) hydrogen gas, H2. "Atomic hydrogen" and "hydrogen atom" in ordinary English use have overlapping, yet distinct, meanings. For example, a water molecule contains two hydrogen atoms, but does not contain atomic hydrogen (which would refer to isolated hydrogen atoms).
Atomic spectroscopy shows that there is a discrete infinite set of states in which a hydrogen (or any) atom can exist, contrary to the predictions of classical physics. Attempts to develop a theoretical understanding of the states of the hydrogen atom have been important to the history of quantum mechanics, since all other atoms can be roughly understood by knowing in detail about this simplest atomic structure.
The most abundant isotope, hydrogen-1, protium, or light hydrogen, contains no neutronsand is simply a proton and an electron. Protium is stable and makes up 99.985% of naturally occurring hydrogen atoms.[2]
Deuterium contains one neutron and one proton in its nucleus. Deuterium is stable and makes up 0.0156% of naturally occurring hydrogen[2] and is used in industrial processes like nuclear reactors and Nuclear Magnetic Resonance.
Tritium contains two neutrons and one proton in its nucleus and is not stable, decaying with a half-life of 12.32 years. Because of its short half-life, tritium does not exist in nature except in trace amounts.
Heavier isotopes of hydrogen are only created artificially in particle accelerators and have half-lives on the order of 10−22 seconds. They are unbound resonances located beyond the neutron drip line; this results in prompt emission of a neutron.
The formulas below are valid for all three isotopes of hydrogen, but slightly different values of the Rydberg constant (correction formula given below) must be used for each hydrogen isotope.
https://en.wikipedia.org/wiki/Hydrogen_atom
The trihydrogen cation or protonated molecular hydrogen is a cation (positive ion) with formula H+
3, consisting of three hydrogen nuclei (protons) sharing two electrons.
The trihydrogen cation is one of the most abundant ions in the universe. It is stable in the interstellar medium (ISM) due to the low temperature and low density of interstellar space. The role that H+
3 plays in the gas-phase chemistry of the ISM is unparalleled by any other molecular ion.
The trihydrogen cation is the simplest triatomic molecule, because its two electrons are the only valence electrons in the system. It is also the simplest example of a three-center two-electron bond system.
https://en.wikipedia.org/wiki/Trihydrogen_cation
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