Loss of electrons
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.
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
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