Template:Base quantities and count

Quantity	Symbol for quantity Q	Symbol for dimension	Name of SI unit	Symbol for SI unit uQ [*]
length	l	L	meter	m
mass	m	M	kilogram	kg
time	t	T	second	s
electric current	I	I	ampere	A
thermodynamic temperature	T	Θ	kelvin	K
amount of substance *,§	nX = NX·NA-1	N	mole	mol
count *,$	NX	X	elementary unit	x
elementary entity *,$	UX	U	elementary unit	x
charge *,€	Qe = NX·zX·e	I·T	coulomb	C = A·s
luminous intensity	Iv	J	candela	cd

[*] »SI base units, except for the canonical 'elementary unit' [x]. The following footnotes are canonical comments.

^* For the quantities n, N, U, and Q, the entity-type X of the elementary entity U_X has to be specified in the text and indicated by a subscript: n_O2; N_ce; Q_e.

^§ Amount n_X is an elementary quantity, converting the elementary unit [x] into moles [mol] using the Avogadro constant, N_A.

^$ Count N_X equals the number of elementary entities U_X. In the SI, the quantity 'count' is explicitly considered as an exception: "Each of the seven base quantities used in the SI is regarded as having its own dimension. .. All other quantities, with the exception of counts, are derived quantities" (Bureau International des Poids et Mesures 2019 The International System of Units (SI)). An elementary entity U_X is not a count (U_X is not a number of U_X). N_X has the dimension X of a count and U_X has the dimension U of an elementary entity, and both quantities have the same unit, the 'elementary unit' [x].

^€ Charge is a derived SI quantity. Charge is an elementary quantity, converting the elementary unit [x] into coulombs [C] using the elementary charge, e, or converting moles [mol] into coulombs [C] using the Faraday constant, F. z_X is the charge number of elementary entity U_X, which is a constant for any defined elementary entity U_X. Q_e = n_X·z_X·F