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Atomic theory is the scientific theory that matter is composed of particles called atoms. The concept that matter is composed of discrete particles is an ancient idea, but gained scientific credence in the 18th and 19th centuries when scientists found it could explain the behaviors of gases and how chemical elements reacted with each other. By the end of the 19th century, atomic theory had gained widespread acceptance in the scientific community.
In chemistry, a hydrogen bond is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted Dn−H···Ac, where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are the second-row elements nitrogen (N), oxygen (O), and fluorine (F).
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p
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In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many intermediate states are known to exist, such as liquid crystal, and some states only exist under extreme conditions, such as Bose–Einstein condensates, neutron-degenerate matter, and quark–gluon plasma. For a complete list of all exotic states of matter, see the list of states of matter.
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In physics, the hydrodynamic quantum analogs refer to experimentally-observed phenomena involving bouncing fluid droplets over a vibrating fluid bath that behave analogously to several quantum-mechanical systems.
Proton tunneling is a type of quantum tunneling involving the instantaneous disappearance of a proton in one site and the appearance of the same proton at an adjacent site separated by a potential barrier. The two available sites are bounded by a double well potential of which its shape, width and height are determined by a set of boundary conditions. According to the WKB approximation, the probability for a particle to tunnel is inversely proportional to its mass and the width of the potential barrier. Electron tunneling is well-known. A proton is about 2000 times more massive than an electron, so it has a much lower probability of tunneling; nevertheless, proton tunneling still occurs especially at low temperatures and high pressures where the width of the potential barrier is decreased.
References
- 1 2 3 4 Michael Schirber (22 April 2016). "Focus: Water Molecule Spreads Out When Caged". Physics. 9 (43). Retrieved 23 April 2016.
- 1 2 Ron Walli. "New state of water molecule discovered". Phys.org . Retrieved 23 April 2016.
- ↑ N. Pugliano. Vibration-Rotation-Tunneling Dynamics in Small Water Clusters, Lawrence Berkeley Laboratory, November 1992, p. 6
- ↑ Richardson, Jeremy O.; et al. (18 March 2016). "Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism". Science. 351 (6279): 1310–1313. Bibcode:2016Sci...351.1310R. doi: 10.1126/science.aae0012 . PMID 26989250.
- ↑ Gorshunov, Boris P.; et al. (29 May 2013). "Quantum Behavior of Water Molecules Confined to Nanocavities in Gemstones". Journal of Physical Chemistry Letters . 4 (12): 2015–2020. doi:10.1021/jz400782j. PMID 26283245. S2CID 19915207.
- ↑ Kolesnikov, Alexander I.; et al. (22 April 2016). "Quantum Tunneling of Water in Beryl: A New State of the Water Molecule". Physical Review Letters . 116 (16): 167802. Bibcode:2016PhRvL.116p7802K. doi: 10.1103/PhysRevLett.116.167802 . PMID 27152824.