REDOX, oxidation numbers, oxidation, and reduction

REDOX chemistry

• reduction-oxidation chemistry

• electron transfer

• oxidation and reduction occur together

oxidation

• half reaction - electron is a product

• anodes

• increase oxidation number

• reducing agents

• loss of electrons

reduction

• decrease oxidation number

• oxidizing agents

• gain electron

• cathodes

• half reaction - electron is a reactant

oxidation numbers

• single/molecular ion - amount of electrons have been lost/gained

• positive - loss of electrons

• negative - gain of electrons

• number given to each atom/ion in a compound to keep track of amount of electrons

rule 1 - free atoms

oxidation number is zero

rule two - fixed ox^#

atoms/ions have fixed oxidation number in compounds

• group one = +1

• group two = +2

• fluorine = -1

• hydrogen = +1

• oxygen = -2

excpetion to hydrogen

oxidation number is -1 in a metal hydride (H is anion)

exception to oxygen

• -1 in peroxide (O₂)

• +2 with fluorine

rule three - ionic compounds

ion’s oxidation number is its charge in ionic form

rule four - compounds/polyatomic ions

sum of all the oxidation numbers must equal the total charge

rule five - complex ions

oxidation number can be determined using charge on complex ion

rules six - electronegativity

more electronegative element is given priority for the Ox^# rule

reducing agent

• oxidized (loses electrons)

• reduce another atom by causing it to gain electrons

• oxidation number incerases

• facilitates oxidization

oxidizing agent

• reduced (gain electrons)

• oxidizes another atom by causing it to lose electrons

• oxidation number of decreases

• facilitates reduction

half reactions

• show gain and loss of electrons

• cannot occur on its own

• electrons must equal the same

• balance mass