Redox Flashcards
(23 cards)
oxidation number/state
oxidation number of an element is a measure of the number of electrons that an atom uses to bond with atoms of another element
ON of potassium fluoride
F = +1
K = -1
ON of sulfur dioxide
S = +4
O = -2
ON of bromine
Br = 0 because not forming bonds with atoms of a different element
how should you give oxidation numbers
always give oxidation ion number of each ion
sum of all ON in a neutral compound is
0
sum of all ON in an ion is equal to the
charge on that ion
ON of any uncombined element e.g H2, Br2 is
0
ON of oxygen in compounds is
-2
EXCEPTION - ON of oxygen in peroxides e.g H2O2 is
-1
ON of hydrogen in a compound is
+1
EXCEPTION - ON of hydrogen in hydrides e.g LiH is
-1
in compound group 1 element has ON of
+1
in compound group 2 element has ON of
+2
in compound group 3 element has ON of
+3
group 7 element can have different ON so assume On is
-1
oxyanions are
negative ions consisting of oxygen and one or more elements and usually end in ‘ate’
redox
reaction where both oxidation and reduction take place
oxidation
loss of electrons/an increase in ON number
reduction
gain of electrons/a decrease in ON number
how to determine if a reaction is redox
- changes in ON of an element
- transfer of electrons to/from an element
oxidising agent
reagent that oxidises (takes electrons from) another species
reducing agent
reagent that (adds electrons to) another species
