The elementary charge or proton charge e has the SI unit coulomb [C], but more strictly coulomb per elementary unit [C·x-1]. -e is the charge per electron. Elementary charge e is the charge per elementary entity H+ with SI unit [C] but canonical SI unit [C·x-1]. When the charge Qel [C] of a number Ne [x] of electrons e is divided by the count Ne, then the particle charge QNX (QNX) charge per elementary entity is obtained, -e = Qel/Ne [C·x-1]. e is also used as an atomic unit.
Abbreviation: e [C·x-1]
Communicated by Gnaiger E (2018-10-18) last update 2020-12-01
Canonical comments on IUPAC definitions in the context of charge
Charge of the proton versus charge per proton
- Proton charge is the elementary charge e [C·x-1], which is charge per count of protons.
Qel ≝ Qelp+ [C]
e ≝ QNp+ = Qel·Np+-1 [C∙x-1]
- The distinction of charge of particles versus charge per single particle is not made sufficiently clear by IUPAC, when defining "-e is the charge of an electron" — it must be corrected to "-e is the charge per electron".
- For comparison, the name "charge density of electrons" is used by IUPAC with symbol ρ [C·m-3]. Dividing ρ by the count concentration of electrons [x·m-3], we obtain the unit [C·x-1] for the electron charge. Therefore, electron charge (or proton charge) is clearly the charge per particle.
Ambiguity of QB
- IUPAC (Cohen 2008 IUPAC Green Book) defines the charge number as
IUPAC: zB = QB·e-1
- Therefore, QB = zB∙e. The subscript in QB indicates per elementary entity B. This is opposite to the subscript in VB as the symbol for the volume of a substance of type B (e.g. VO2 [L]). For consistency with this convention, the symbol QelB or QelX [C] is used for indicating charge of a substance of type B or X, distinguished from particle charge as the quantity of charge per elementary entity X with symbol QNX [C∙x-1]. To avoid too long and multiple subscript levels, QNX is used instead of QUX, and the ‘el’ is dropped from QelNX. The particle charge QNH+ per hydrogen ion is identical to the definition of the elementary charge e. Therefore, the charge number of the hydrogen ion is zH+ = QNH+/e = 1. In summary:
zB = QNB·e-1
QNB = QelB·NB-1 [C∙x-1]
- Bioblast links: Charge - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
- Normalization of charge and iconic symbols
- Iconic symbols show the quantity, the format of the normalization in the subscript (N, n, e), and the entity specified in the subscript (X). The normalized quantities are per X. In the quantities QelX, NX, nX, VX, mX, the subscript X without attachment to a format indicates the quantity of X.
Quantity Unit Normalized for quantity Unit Iconic symbol Unit Practical symbol Quantity charge QelX [C] / count NX [x] = QNX [C·x-1] particle charge (IUPAC: QB) charge QelX [C] / amount nX [mol] = QnX [C·mol-1] charge number times Faraday constant charge QelX [C] / volume VX [m3] = QVX [C·m-3] ρel charge density charge QelX [C] / mass mX [kg] = QmX [C·kg-1] specific charge count NX [x] / charge QelX [C] = NeX [x·C-1] amount nX [mol] / charge QelX [C] = neX [mol·C-1] volume VX [m3] / charge QelX [C] = VeX [m3·C-1] ρel-1 mass mX [kg] / charge QelX [C] = meX [kg·C-1]
- Bioblast links: SI base units - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
- Entity, count, and number, and SI base quantities / SI base units
Quantity name Symbol Unit name Symbol Comment elementary UX elementary unit [x] UX, UB; [x] not in SI count NX elementary unit [x] NX, NB; [x] not in SI number N - dimensionless = NX·UX-1 amount of substance nB mole [mol] nX, nB electric current I ampere [A] A = C·s-1 time t second [s] length l meter [m] SI: metre mass m kilogram [kg] thermodynamic temperature T kelvin [K] luminous intensity IV candela [cd]
- Bureau International des Poids et Mesures (2019) The International System of Units (SI). 9th edition:117-216 ISBN 978-92-822-2272-0. - »Bioblast link«
- Cohen ER, Cvitas T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor HL (2008) Quantities, Units and Symbols in Physical Chemistry. IUPAC Green Book 3rd Edition, 2nd Printing, IUPAC & RSC Publishing, Cambridge. - »Bioblast link«
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2 - »Bioblast link«
- Gnaiger Erich (2020) Canonical reviewer's comments on: Bureau International des Poids et Mesures (2019) The International System of Units (SI) 9th ed. MitoFit Preprint Arch 2020.4 doi:10.26124/mitofit:200004.
MitoPedia concepts: Ergodynamics