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. This includes ions as well as neutral atoms and, unless otherwise stated, for the purposes of this discussion it should be assumed that the term atom includes ions.
The term atomic physics is often associated with nuclear power and nuclear bombs, due to the synonymous use of atomic and nuclear in standard English. However, 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.
A chemical property is any of a material's properties that becomes evident during a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity. Simply speaking, chemical properties cannot be determined just by viewing or touching the substance; the substance's internal structure must be affected for its chemical properties to be investigated. However a catalytic property would also be a chemical property.
Chemical properties can be contrasted with physical properties, which can be discerned without changing the substance's structure. However, for many properties within the scope of physical chemistry, and other disciplines at the boundary between chemistry and physics, the distinction may be a matter of researcher's perspective. Material properties, both physical and chemical, can be viewed as supervenient; i.e., secondary to the underlying reality. Several layers of superveniency]clarification needed[ are possible.
Captain Atom is a fictional character, a comic book superhero that has existed in three basic incarnations. Created by writer Joe Gill and artist/co-writer Steve Ditko, he first appeared in Space Adventures #33 (March 1960). Captain Atom was created for Charlton Comics but was later acquired by DC Comics and revised for DC’s post-Crisis continuity. In 2011, DC Comics relaunched its superhero comics and restarted the histories of some characters from scratch, including Captain Atom, giving him a new origin, appearance and slightly altered powers. The character of Captain Atom was the inspiration for the character Doctor Manhattan who was featured in the miniseries (and later live-action film adaptation) Watchmen.
Throughout the years, the character has been featured in several moderate-to-short lived eponymous series, and has been a member of several different versions of DC’s flagship superhero team Justice League. In all incarnations, the character initially worked for the military. In the Charlton Comics continuity, he was a scientist named Allen Adam and gained his abilities by accident when he was seemingly "atomized" and then somehow reformed his body, now existing as an atomic-powered being. In both DC Comics incarnations, he is Air Force pilot Nathaniel Adam who was used as a test subject in a scientific experiment and wound up seemingly disintegrated in the process, only to reappear later as Captain Atom, now blessed with superhuman abilities. Over the years, DC has attempted to reinvent the character a number of times. For a period, the character assumed the mantle of the supervillain Monarch, and in 2005 DC attempted to retell the Captain Atom story with an entirely new character, Breach, who was subsequently discarded. In the new continuity following DC's 2011 relaunch, Captain Atom has never been a member of the Justice League and the team views him with distrust; his character origin and abilities were also revised.
The monoisotopic mass is the sum of the masses of the atoms in a molecule using the unbound, ground-state, rest mass of the principal (most abundant) isotope for each element instead of the isotopic average mass. For typical organic compounds, where the monoisotopic mass is most commonly used, this also results in the lightest isotope being selected. For some heavier atoms such as iron and argon the principle isotope is not the lightest isotope. The term is designed for measurements in mass spectrometry primarily with smaller molecules. It is not typically useful as a concept in physics or general chemistry. Monoisotopic mass is typically expressed in unified atomic mass units (u), also called daltons (Da).
The mass spectral peak representing the monoisotopic mass is not always the most abundant isotopic peak in a spectrum despite it containing the most abundant isotope for each atom. This is because as the number of atoms in a molecule increases, the probability that the entire molecule contains at least one heavy isotope atom also increases. For example if there are 100 carbon atoms in a molecule each of which has an approximately 1% chance of being a heavy isotope the whole molecule is highly likely to contain at least one heavy isotope atom and the most abundant isotopic composition will no longer be the same as the monoisotopic peak.