Notation used in chemical equations, apparatus diagrams and physical constants.
An italic lower-case c, denoting the speed of light in vacuum.
An italic lower-case h, denoting the quantum of action.
An italic k, often subscripted B, relating temperature to energy.
A capital N with subscript A, the number of entities in a mole.
An italic lower-case e, the magnitude of the charge on a proton.
An italic capital G, the constant in Newton's law of gravitation.
A Greek lambda, denoting the distance between successive wave peaks.
A t with subscript one-half, the time for half a quantity to decay.
A single-headed arrow separating reactants from products.
Two half-headed arrows pointing opposite ways, marking a reversible reaction.
A double-headed straight arrow between two drawn structures.
A downward arrow after a formula, marking a solid falling out of solution.
An upward arrow after a formula, marking a gas leaving the reaction.
A hexagon with an inscribed circle, representing delocalised aromatic bonding.
A zigzag of lines whose vertices are carbon atoms, with hydrogens left undrawn.
A capital delta before an H, denoting heat absorbed or released.
An element symbol with mass number above and atomic number below, to its left.
A flask with a vertical condenser above it, in an apparatus diagram.
A formula written above a reaction arrow, naming a catalyst.
Two parallel lines between atoms, representing a shared double bond.