ch 18 redox reactions

"oil rig"

oxidation is loss, reduction is gain

oxidation

complete or partial loss of electrons

reduction

complete or partial gain of electrons

redox equations can involve:

monatomic cations/anions, molecular compounds, and polyatomic ions

oxidation number

= ionic charge

uncombined solitary elements oxidation numbers

= 0

uncombined allotropes of elements oxidation numbers

= 0

oxidation agent

a substance that oxidizes another substance, becoming reduced in the process by accepting/gaining electron(s)

reducing agent

a substance that reduces another substance, becoming oxidized in the process by releasing/losing electron(s)

redox equations with molecular compounds

no ions are formed and no electrons are transferred in these

redox and electronegativity

use this to identify what is oxidized or reduced (periodic trend: electronegativity increases toward fluorine)

low electronegativity

loses electrons easily = oxidized = reducing agent

high electronegativity

gains electrons easily = reduced = oxidizing agent

uncombined solitary elements, "super seven," allotropes

oxidation number = 0

monatomic ion oxidation number

= its charge

molecule or polyatomic ion oxidation number

the most electronegative element is assigned its usual charge as if it were an independent ion

F oxidation number

always -1 when bonded to another element

O oxidation number

always -2 except in the peroxide ion ((O2)-2 where it is -1)

H oxidation number

+1 unless in a metal hydride (such as potassium hydride HS) where it is -1

the total of all oxidation numbers in a neutral compound

= 0

the total of all oxidation numbers in a polyatomic ion

= the charge for the whole ion