An electronic state having a higher energy than the ground state.
Exothermic reaction
A reaction that gives off heat (negative ∆H) to the surroundings as the reaction proceeds.
f subshell
The subshells corresponding to the angular momentum quantum number l = 3, found in the fourth
and higher principal energy levels, each containing seven orbitals.
Faraday (F)
The total charge on 1 mole of electrons (1 F = 96,487 coulombs).
Fatty acids
Carboxylic acids with long hydrocarbon chains, derived from the hydrolysis of fats.
First law of thermodynamics
The law stating that the total energy of a system and its surroundings remains constant. Also
expressed as ∆E = Q – W: the change in energy of a system is equal to the heat added to it minus the
work done by it.
Formal charge
The conventional assignment of charges to individual atoms of a Lewis formula for a molecule, used
to keep track of valence electrons. Defined as the total number of valence electrons in the free atom
minus the total number of nonbonding electrons minus one-half the total number of bonding
electrons.
Freezing point
At a given pressure, the temperature at which the solid and liquid phases of a substance coexist in
equilibrium.