A-level Chemistry/OCR (Salters)/Physical quantities

Physical quantity	Symbol for quantity	Unit(s)*	Symbol for unit(s)
concentration	c	mole per cubic metre mole per litre mole per cubic decimetre	mol m−3 mol l−1 mol dm−3
energy	E	joule kilojoule	J kJ
frequency	ν (Greek letter nu)	hertz reciprocal second	Hz s−1
charge	Q	coulomb	C
amount of substance	n	mole	mol
mass	m	kilogram gram	kg g
molar mass	M	gram per mole	g mol−1
relative molecular mass	Mr	no unit	no unit
wavelength	λ	metre	m

* Note that SI units are shown in bold

Notes: An SI unit named after a person has the first letter of its symbol capitalised, but the full name of the unit written out is all lower case. For example, the unit of energy named after James Joule is called the joule (lower case) and has the symbol J (upper case). An SI unit that is not named after a person has an all-lowercase name and symbol. For example, the unit of amount of substance is called the mole (lowercase) and has the symbol mol (lowercase). The symbols for quantities are always in italic type, whereas the symbols for units are always in upright (normal) type.