4.3 Redox Flashcards
What is the oxidation number
Based on a set of rules that apply to atoms and can be thought of as the number of electrons involved in bonding to a different element.
The oxidation number is always ____ for elements
In a pure element, any bonding is to atoms of the same element so H2, O2, P4, S8
zero
Each atom in a compound has an oxidation number
Where is the sign placed in an oxidation number
BEFORE THE NUMBER
Ie. -2 or +2
Sum of oxidation numbers =
total charge
When are roman numerals used to show charges
When ions of different charges can be formed
Eg. Iron (II) - Fe2+
What is oxidation (original idea)
The addition of oxygen
What is reduction (original idea)
The removal of oxygen
What is a redox reaction
A reaction that involves both oxidation and reduction
What is oxidation (new idea)
The loss of electrons
What is reduction (new idea)
The gain of electrons
How to remember oxidation and reduction
OIL RIG
Oxidation Is Loss
Reduction Is Gain
Redox in terms of oxidation number
Reduction is a DECREASE in oxidation number
Oxidation is an INCREASE in oxidation number
Redox reactions of acids and metals
metal + acid -> salt + hydrogen
Oxidation number of oxygen (combined)
-2
Oxidation number of Hydrogen (combined)
+1
