3 Flashcards
What is an oxidation number?
The number of electrons an atom uses to bond with any other atom
Define oxidation in terms of electron transfer and oxidation number
Oxidation is
● Loss of electrons
● An increase in oxidation number
Define reduction in terms of electron transfer and oxidation number
Reduction is
● Gain of electrons
● A decrease in oxidation number
What is a redox reaction?
A reaction in which both oxidation and reduction takes place
What is the oxidation number of an uncombined element such as C, H, O2?
0
What is the oxidation number of group 1 elements?
+1
What is the oxidation number of group 2 elements?
+2
What is the oxidation number of aluminium?
+3
What is the oxidation number of fluorine?
-1
What is the oxidation number of the rest of the group 7 elements?
-1
Unless they are bonded with fluorine, then it is +1
What is the oxidation number of hydrogen?
+1
Unless they are in a metal hydride, then it is -1
What is the oxidation number of oxygen?
-2
Unless they are in peroxides, then it is -1
What is the oxidation number of oxygen in peroxides?
-1
What is the oxidation number of hydrogen in metal hydrides such as LiH?
-1
What is the oxidation number of a simple ion?
Charge on the ion
E.g Na+ → +1 ; Cl- → -1
When an element has more than one stable oxidation number how is it indicated?
Written as a Roman numeral
What is the oxidation number of Fe in iron (III) chloride?
+3
What are oxyanions?
Negative ions that have an element along with oxygen
What is the oxidation number of a metal?
0, because it is an uncombined element
What is an oxidising agent?
Species that gains electrons
It oxidises something and is reduced itself
What is a reducing agent?
Species that lose electrons.
It reduces something and is oxidised itself
Define the term disproportionation?
Where in a redox reaction, the oxidation states of atoms of the same element, increase for some atoms, whereas decrease for some atoms.
A reaction in which a substance is simultaneously oxidized and reduced, giving two different products
