Oxidation State Rules Flashcards
What is oxidation state
The hypothetical charge on an atom assuming that the bonding is completely ionic
What other type of bonding can have oxidation state
Covalent (molecules)
What does oxidation state tell us in ionic bonds
Which elements have gained or lost electrons
What does oxidation state in covalent bonds tell us
It tells us how electrons are distributed between elements with different electronegativities
How is oxidation state useful
Can be used as a tool to see how redox reactions oxidise or reduce atoms and elements
Rule one of oxidation states
Uncombined elements have an oxidation state of 0
Rule 2 of oxidation states
The sum of all the oxidation states in a compound = 0 since all compounds are electrically neutral
Rule 3
Some elements have pre assigned values
What is the oxidation state of hydrogen
+1 (except in metal hydrides eg NaH, where it is -1)
What is the oxidation state of group 1 elements
Always +1
What is the oxidation state of group 2
Always +2
What is the oxidation state of aluminium
Always +3
What is the oxidation state of Oxygen
-2(except in peroxide where it is -1, and the compound OF2,where it is +2)
Oxidation state of fluorine
Always -1
Oxidation state of chlorine
-1 (except in compounds with F and O,where it has a positive values)
Rule 4 of oxidation states
The sum of oxidation states of a complex ion, such as NH4^+ or SO4^2-,equals the charge on the ion
Rule 5 of oxidation states
In a compound the most electronegative element always has a negative oxidation state
