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atom : the smallest particle of an element that can exist either alone or in combination — Webster
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Atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small; typical sizes are around 100 picometers (a ten-billionth of a meter, in the short scale).
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and typically a similar number of neutrons. Protons and neutrons are called nucleons. More than 99.94% of an atom’s mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, that atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively, and it is called an ion.
The electrons of an atom are attracted to the protons in an atomic nucleus by this electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by a different force, the nuclear force, which is usually stronger than the electromagnetic force repelling the positively charged protons from one another. Under certain circumstances, the repelling electromagnetic force becomes stronger than the nuclear force, and nucleons can be ejected from the nucleus, leaving behind a different element: nuclear decay resulting in nuclear transmutation.
The number of protons in the nucleus defines to what chemical element the atom belongs: for example, all copper atoms contain 29 protons. The number of neutrons defines the isotope of the element. The number of electrons influences the magnetic properties of an atom. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature and is the subject of the discipline of chemistry. — Wikipedia
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Atomic Physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and the processes by which these arrangements change.
The term atomic physics can be associated with nuclear power and nuclear weapons, due to the synonymous use of atomic and nuclear in standard English. Physicists distinguish between atomic physics — which deals with the atom as a system consisting of a nucleus and electrons — and nuclear physics, which considers atomic nuclei alone. — Wikipedia
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions. Other forms of nuclear matter are also studied. Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons. — Wikipedia
Preservation
History
How Can You See an Atom? – Legends of Chemistry (American Chemical Society)
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National Museum of Nuclear Science & History (Albuquerque, New Mexico)
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WorldCat, Library of Congress, UPenn Online Books, Open Library
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https://fusedweb.llnl.gov/
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Atom in a Box: Real-Time Visualization of the Quantum Mechanical Atomic Orbitals (Dauger Research)
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Scientist Splits Atom, Finds Toy Prize Inside (Satire Wire)
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OEDILF: The Omnificent English Dictionary In Limerick Form
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Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.
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Self-imaging of a molecule by its own electrons
on September 17, 2020 at 1:39 pm
One of the long-standing goals of research on the light-induced dynamics of molecules is to observe time-dependent changes in the structure of molecules, which result from the absorption of light, as directly and unambiguously as possible. To this end, researchers have developed and applied a plethora of approaches. Of particular promise among these approaches are several methods developed in the last years that rely on diffraction (of light or electrons) as means of encoding the internuclear […]
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Analyzing molecular structures in more...
on September 16, 2020 at 2:39 pm
Chemistry and structural biology use the standard methods of NMR spectroscopy (NMR = nuclear magnetic resonance) to examine the structure of molecules including large molecules like proteins in solution. The NMR active nuclei, such as hydrogen atoms, are excited using radiofrequency pulses in spectrometers with strong magnetic fields. The different environments of the nuclei can be detected and conclusions about the molecular structure can be drawn from analysis of the generated spectra.
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New neutron source in Canada would spur...
on September 15, 2020 at 12:53 pm
Technological progress owes much to our scientific understanding of the materials we use to build the world around us, from longer-lasting cell-phone batteries to new medicines.
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On the road to conductors of the future
on September 14, 2020 at 3:16 pm
Superconducting wires can transport electricity without loss. This would allow for less power production, reducing both costs and greenhouse gasses. Unfortunately, extensive cooling stands in the way, because existing superconductors only lose their resistance at extremely low temperatures. In the journal Angewandte Chemie, scientist have now introduced new findings about hydrogen sulfide in the H3S form, and its deuterium analog D3S, which become superconducting at the relatively high […]
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on September 11, 2020 at 11:21 am
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