Chem 12 U1C3 - Redox Chemistry

redox reactions

oxidation and reduction, involve the transfer of electrons

oxidation

loss of electrons

reduction

gain of electrons

why must reduction and oxidation reactions occur simultaneously

to facilitate the transfer of electrons

reducing agent/reductant

causes another substance to be reduced and is itself oxidised

oxidising agent/oxidant

causes another species to be oxidised and is itself reduced

how do metals become chemically stable

losing some or all of their valence electrons to form cations

how do non-metals become chemically stable

gaining electrons to form anions

ionisation energy

energy required to remove one electron from a gaseous species

how many ionisation energies does an element have

as many as it does electrons

corrosion

oxidation of a metal in the presence of air to form the metal oxide

rust

corrosion of iron

passivating metal

a metal that forms an impervious oxide layer on its surface which prevents further corrosion

oxidation state

an indication of the number of electrons an atom would gain or lose to get to its present state

the oxidation state of any element is

0

the oxidation state of a monatomic ion is

the same as the charge on the ion

the oxidation state of hydrogen in compounds is always __ , except when forming hydrides when it is __

+1, -1

the oxidation state of oxygen in any compound is always___ , except in peroxides where it is ___ and in F2O where it is __

-2, -1, +2

in a neutral compound, the sum of the oxidation states must always equal

0

in ions, the sum of the oxidation states must equal

the charge on that ion

the most electronegative species in a compound is always assigned the _______ oxidation state; the less electronegative species is assigned the ______ oxidation state

negative, positive

acryonym for balancing redox reactions

KOHES

KOHES stands for

key element, oxygen, hydrogen, electrons, states

oxidation occurs when oxidation state ____, becomes more _____

increases, positive

reduction occurs when oxidation state _____, becomes more ______

decreases, negative

a more reactive metal is _____ likely to oxidise

more

electrolyte

a substance that conducts an electric current

half equation

when an equation has been split into its two components, oxidation and reduction