REDOX

  • calculate the oxidation state of specified atoms in formulae (including ions) 
  • explain which species have been oxidised and which reduced in a redox reaction;
  • use systematic nomenclature to name inorganic compounds
  • describe redox reactions of s- and p-block elements and their compounds in terms of electron transfer,
  • using halfequations to represent the oxidation and reduction reactions, and
  • defining oxidation and reduction as loss and gain of electrons;
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OILRIG

Oxidation

Is

Loss of electrons

Reduction

Is

Gain of electrons

  • In an overall reaction, oxidation and reduction must go together 
  • electron gain must equal the electron loss in the complete and fully balanced equation
  • An electron acceptor is an oxidising agent and therefore gets reduced in its action, so there is a decrease in the oxidation number/state of one of the atoms of the oxidising agent.
  • An electron donor is a reducing agent and therefore gets oxidised in the process, so there is an increase in the oxidation number/state of one of the atoms of the reducing agent.

 

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Oxidation state and rules

the oxidation state can be defined as:

 the number of electrons which must be added or removed to leave the element in its electrically neutral elemental state. 

  • The oxidation number of anything in elemental form is 0.
  • Fluorine is assigned an oxidation number of -1 in compounds (Fl -1)
  • Oxygen is assigned an oxidation number of -2 in compounds (O -2)
  • Hydrogen is assigned an oxidation of +1 in compounds (H +1)
  • Group I elements (Alkali Metals) are assigned an oxidation number of +1 in compounds (G1 +1)
  • Group II elements (Alkaline-earth metals) are assigned an oxidation number of +2 in compounds (G2 +2)
  • Any monatomic ion has an oxidation number equal to its charge
  • The sum of the oxidation numbers of all the atoms in a formula equals the electrical charge shown with the formula

 

 

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REDOX of -s block and -p block elements

-Elements in the -s block will be oxidised (loss of electrons)

-This makes them reducing agents

 

-Most p-block elements have both positive and negative oxidation states.
-The maximum is the last digit of the group number (except for oxygen and fluorine for which the maximum is 0).

-The minimum is the Group Number - 18

 

 

 

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