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Nuclear Energy Science Tracer Bullet (Library of Congress)
Nuclear Power (Wolfram Alpha)
These are organized by a classification scheme developed exclusively for Cosma. More…
CODATA Internationally recommended values of the Fundamental Physical Constants, Atomic and Nuclear (NIST Reference on Constants, Units and Uncertainty)
Radiation, Radioactivity & Radiobiology (Martindale’s Reference Desk)
atom : the smallest particle of an element that can exist either alone or in combination — Webster
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
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
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.
- The Swiss Alps continue to rise: Evidence from...on November 27, 2020 at 5:50 pm
An international team of geologists, headed by members of the University of Bern, has shown for the first time that the Swiss Alps are being lifted faster than they are being lowered through erosion—and are thus growing even higher. To do this, the researchers quantified the erosion of the Alps with the help of isotopes measured in the sand of more than 350 rivers throughout the European Alps. These isotopes are formed by cosmic rays and bear information on the Earth's surface erosion.
- Regulating the reactivity of black phosphorous...on November 24, 2020 at 2:30 pm
Chemists can rationally regulate the reactivity of molecules and functional groups in both industrial and laboratory-based synthetic organic chemistry processes. The concept can be applied to inorganic nanomaterials including two-dimensional (2-D) black phosphorus (BP) nanosheets. For example, scientists can "shut down" the high reactivity of few layer or monolayer black phosphorus, when the compound is not in use, to resume its activity upon application. In a new report now published on […]
- A new beat in quantum matteron November 23, 2020 at 6:26 pm
Oscillatory behaviors are ubiquitous in nature, ranging from the orbits of planets to the periodic motion of a swing. In pure crystalline systems, presenting a perfect spatially-periodic structure, the fundamental laws of quantum physics predict a remarkable and counter-intuitive oscillatory behavior: when subjected to a weak electric force, the electrons in the material do not undergo a net drift, but rather oscillate in space, a phenomenon known as Bloch oscillations. Ultracold atoms immersed […]
- Folding of SARS-CoV2 genome reveals drug...on November 23, 2020 at 2:17 pm
The genetic code of the SARS-CoV2 virus is exactly 29,902 characters long, strung through a long RNA molecule. It contains the information for the production of 27 proteins. This is not much compared to the possible 40,000 kinds of protein that a human cell can produce. Viruses, however, use the metabolic processes of their host cells to multiply. Crucial to this strategy is that viruses can precisely control the synthesis of their own proteins.
- Scientists observe directed energy transport...on November 23, 2020 at 12:59 pm
When light falls on a material, such as a green leaf or the retina, certain molecules transport energy and charge. This ultimately leads to the separation of charges and the generation of electricity. Molecular funnels, so-called conical intersections, ensure that this transport is highly efficient and directed.