The atomic ratio is a measure of the
ratio
In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
of atoms of one kind (i) to another kind (j). A closely related concept is the atomic percent (or at.%), which gives the percentage of one kind of atom relative to the total number of atoms.
The
molecular
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
equivalents of these concepts are the molar fraction, or
molar percent
The atomic ratio is a measure of the ratio of atoms of one kind (i) to another kind (j). A closely related concept is the atomic percent (or at.%), which gives the percentage of one kind of atom relative to the total number of atoms. The molecula ...
.
Atoms
Mathematically, the ''atomic percent'' is
:
%
where ''N''
i are the number of atoms of interest and ''N''
tot are the total number of atoms, while the ''atomic ratio'' is
:
For example, the ''atomic percent'' of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
in
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
(H
2O) is , while the ''atomic ratio'' of hydrogen to oxygen is .
Isotopes
Another application is in
radiochemistry
Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads t ...
, where this may refer to
isotopic ratio
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomi ...
s or
isotopic abundance
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomi ...
s. Mathematically, the ''isotopic abundance'' is
:
where ''N''
i are the number of atoms of the isotope of interest and ''N''
tot is the total number of atoms, while the ''atomic ratio'' is
:
For example, the ''isotopic ratio'' of
deuterium
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
(D) to
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
(H) in
heavy water is roughly (corresponding to an ''isotopic abundance'' of 0.00014%).
Doping in laser physics
In
laser physics
Laser science or laser physics is a branch of optics that describes the theory and practice of lasers.
Laser science is principally concerned with quantum electronics, laser construction, optical cavity design, the physics of producing a popul ...
however, the ''atomic ratio'' may refer to the
doping
Doping may refer to:
* Doping, adding a dopant to something
* Doping (semiconductor), intentionally introducing impurities into an extremely pure semiconductor to change its electrical properties
* Aircraft dope, a lacquer that is applied to fabr ...
ratio or the doping fraction.
*For example, theoretically, a 100% ''doping ratio'' of
Yb : Y3Al5O12 is pure Yb
3Al
5O
12.
*The ''doping fraction'' equals,
::::::::
See also
*
Table of concentration measures
References
Physical chemistry
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