ch4- acids and redox

• The number of electrons an atom uses to bond with any other atom is referred to as its oxidation number.
• The oxidation number of an uncombined element such as C, H, O 2 is 0.
• The oxidation number of combined oxygen such as in H 2 O is -2.
• The oxidation number of oxygen in peroxides is -1.
• The oxidation number of combined hydrogen such as in NH 3 , H 2 S is +1.
• The oxidation number of combined hydrogen in metal hydrides such as LiH is -1.
• The oxidation number of a simple ion is the charge on the ion, for example, Na + → +1; Cl - → -1.
• The oxidation number of a metal is 0 because it is an uncombined element.
• The oxidation number of Fe in iron (III) chloride is +3.
• The oxidation number of S in SO 4 2- is +6 because, combined oxygen has an oxidation number of -2.
• Oxyanions are negative ions that have an element along with oxygen.
• A redox reaction is a reaction in which both oxidation and reduction takes place.
• Oxidation is the loss of electrons and an increase in oxidation number.
• When an element has more than one stable oxidation number, it is indicated as a Roman numeral.
• Reduction is the gain of electrons and a decrease in oxidation number.
• The oxidation number of combined fluorine such as in NaF, CaF 2 is -1.