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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 future of particle accelerators is hereon April 16, 2021 at 8:55 pm
When the Electron Ion Collider received the go-ahead in January 2020, it became the only new major accelerator in the works anywhere in the world.
- Scientists report remarkable enhancement of...on April 16, 2021 at 2:45 pm
It is always exciting to find new isotopes with extreme neutron/proton numbers in nuclear physics research. In the region of heavy nuclei, α-decay is one of the pervasive decay modes and plays an essential role in searching for new isotopes. However, even after about a century of studying α-decay, scientists still cannot perfectly describe how the α-particle is formed at the surface of the nucleus before its emission.
- Research finds a potential new 'silver bullet'...on April 16, 2021 at 12:41 pm
ANSTO has contributed to a comprehensive investigation of a promising type of nanoparticle that could potentially be used for intractable brain cancers in a combined therapy.
- Engineers improve performance of high-temperature...on April 15, 2021 at 7:31 pm
Florida State University researchers have discovered a novel way to improve the performance of electrical wires used as high-temperature superconductors (HTS), findings that have the potential to power a new generation of particle accelerators.
- Process simultaneously removes toxic metals and...on April 15, 2021 at 6:00 pm
University of California, Berkeley, chemists have discovered a way to simplify the removal of toxic metals. like mercury and boron. during desalination to produce clean water, while at the same time potentially capturing valuable metals, such as gold.