Redox Flashcards
Oxidation numbers
-In Redox reactions, electrons are transferred from one chemical to another,
-OIL,RIG: Oxidation is loss of electrons whereas Reduction is the gain of electrons
-Oxidation numbers tell us about how electrons are lost or gained in a reaction, eg an atom of Magnesium that has lost two electrons to form a magnesium ion, it can be written as Mg2+ (where the +2 (The sign comes first for Oxidation Numbers) is the Oxidation number). It is defined as, The charge that an atom would have if the compound was composed of ions
-In a pure element, the Oxidation number is always zero
Oxidation Numbers in Non-metals
Element : Oxidation Number : exceptions:
F : -1 :
O : -2 : -1 in peroxides, +2 when reacted with F
Cl,Br,I : -1 : can be positive when bonded to F or O
Due to their high electronegativity
H : +1 : -1 in metal hydrides eg LiH
Oxidation in Metals
Element : Oxidation number:
Group 1: Always +1
Group 2: Always +2
Group 3: Always +3
Transition metals: Variable
Oxidation numbers in compounds
-A compound always has an overall charge of zero unless stated otherwise
-Therfore, we can use the facts about the charges of non-metals and metals to work out unknown charges
Oxidation numbers in reactions
-We can write the change in oxidation numbers across an equation to show what chemicals have been reduced and oxidised
-For Ionic equations, spectator ions, or chemicals where the charge has not changed across the reaction can be removed
Disproportionation
-Disproportionation is simply when one species of a chemical becomes both reduced and oxidised in a single reaction:
Half equations
-Half equations are simply an equation to demonstrate the reduction or oxidation of one chemical and its interaction with electrons, e.g:
Mg —> Mg^2+ + 2e^-
What is an oxidising agent
-The chemical that accepts electrons is called the oxidising agent
What is the reducing agent?
The chemical that donates electrons is the reducing agent
