redox

what is oxidation number

the amount of electrons an atom loses/gains while bonding

what are the rules for oxidation

-pure elements (H₂,O₂)always have an oxidation number of 0

-place the oxidation number before the element

-all the oxidation numbers in a molecule will equal 0

-molecules don’t have an oxidation number unless its a charged molecule

what is oxidation and reduction (oxygen)

oxidation - gain of oxygen

reduction - loss of oxygen

what is oxidation and reduction (electrons)

oxidation - loss of electrons

reduction - gain of electrons

what is oxidation and reduction (oxidation number)

oxidation - increase in oxidation number

reduction - decrease in oxidation number c

common trends for oxidation number

metals - always positive

transition metals can change oxidation number

group 4 elements change a lot

non metals - mostly negative

oxygen - mostly -2

hydrogen - mostly +1

fluorine - always -1

some exceptions in oxidation number

• oxygen becomes positive when with fluorine (FlO)

• oxygen becomes -1 when in a peroxide (C-O-O-C)

• in metal hydrides hydrogen becomes -1

what are spectator ions

ions that remain unchanged in the reaction

Roman numerals

sometimes to show what oxidation number an element has Roman numerals are placed at the end of the name to show the oxidation number

what is a redox reaction

a reaction where a species gets oxidised and another species gets reduced

what is a disproportionation reaction

a reaction where an element undergoes both oxidation and reduction

example of a disproportionation reaction

how does redox relate to electronegativity

most of the elements that have a negative oxidation number have a high electronegativity (Fl)

so they are more likely to attract the negative electrons so that’s why they have a negative oxidation number as they gain electrons