atomic mass unit (u)	mass 12C	1.6605402x10-27 kg
electric charge (coulomb)	e	1.60217733x10-19 C
speed of light (vacuum)	c	299792458 m/s (exact)

Particle	Mass	Charge	Half-life
	(in u)	(in electron charge, e)	(in seconds)
proton, p	1.007276	+1	stable
neutron, n	1.008665	0	624
electron, e or e-	0.000549	-1	stable
neutrino,	> 0	0	stable*
antiproton,	1.007276	-1	stable†
antineutron,	1.008665	0	624†
positron, e+	0.000549	+1	stable
antineutrino,	> 0	0	stable*
muon, m±	0.10565	+1, -1	3.17x10-6
pion, p±	0.14	+1, -1	3.76x10-8
pion, p0	0.14	0	6.63x10-17
photon, g	0	0	stable
gluon, g	0	0
up quark, u	approximately 0.005	+2/3
down quark, d	approximately 0.01	-1/3
strange quark, s	0.1 to 0.3	-1/3
charm quark, c	1.0 to 1.6	+2/3
bottom quark, b	4.1 to 4.5	-1/3
top quark, t	180 ± 12	+2/3
1H atom	1.007825	0	stable
2H nucleus	2.013553	+1	stable
2H atom	2.014102	0	stable
3H nucleus	3.015500	+1	3.88x108
3H atom	3.016049	0	3.88x108
3He nucleus	3.014932	+2	stable
3He atom	3.016029	0	stable
4He nucleus	4.001506	+2	stable
4He atom	4.002603	0	stable
12C atom	12.000000	0	stable
238U atom	238.050785	0	1.41x1017

^† Antiparticles are assumed to have same half-life as particles.
*Neutrinos (antineutrinos) can change into an other one of the same type.

From the Review of Particle Properties, R. M. Barnett et al., Physical Review D54, 1 (1996).

International System of Units (SI)–SI prefixes

value	name	symbol
10-24	yocto	y
10-21	zepto	z
10-18	atto	a
10-15	femto	f
10-12	pico	p
10-9	nano	n
10-6	micro	m
10-3	milli	m
10-2	centi	c
10-1	deci	d
10	deca	da
102	hecto	h
103	kilo	k
106	mega	M
109	giga	G
1012	tera	T
1015	peta	P
1018	exa	E
1021	zetta	Z
1024	yotta	Y

Example of a Branching Ratio

226Ac	Æ	Th + e- +	83%
226Ac + e—	Æ	226Fr +	17%
226Ac	Æ	222Fr + 4He	0.006%