3.1.7 - oxidation, reduction + redox

what does redox mean? (1)

reactions which involve both reduction and oxidation

what is oxidation? (1)

the process of electron loss

what is reduction? (1)

the process of electron gain

what is an oxidising agent? (1)

an electron acceptor

what is a reducing agent? (1)

an electron donor

what is the oxidation state of elements not combined with others? (1)

0

what is the oxidation state of oxygen in compounds, except in peroxides? (1)

-2

what is the oxidation state of oxygen in peroxides (e.g. H₂O₂)? (1)

-1

what is the oxidation state of hydrogen in compounds, except in metal hydrides? (1)

+1

what is the oxidation state of hydrogen in metal hydrides (e.g., NaH)? (1)

-1

what is the oxidation state of group I metals in compounds? (1)

+1

what is the oxidation state of group II metals in compounds? (1)

+2

what is the usual oxidation state of group 7 elements in compounds? (1)

-1

what must the sum of oxidation states of all atoms and ions in a compound equal?

0

what must the sum of oxidation states in a polyatomic ion equal?

the charge on the ion

what does an increase in oxidation state indicate? (1)

oxidation

what does a decrease in oxidation state indicate? (1)

reduction

what is the order of balancing half equations? (5)

1. balance atoms apart from hydrogen or oxygen

2. balance oxygen using water

3. balance hydrogen using H+

4. balance charge using electrons

5. double check it’s all balanced

what is the range of oxidation states determined by?

position of element in periodic table:

• max num of electrons that can be lost or gained before another shell of electrons is affected determines how many electrons element can lose or gain

  • group usually shows how many electrons element can lose