Oxidation numbers

Question 1

oxidation number

Answer 1

how many electrons are gained or lost by an element when atoms turn into ions and vice versa

Question 2

oxidation - oxidation numbers

Answer 2

loss of electrons and a shift to move positive oxidation numbers

Question 3

reduction - oxidation numbers

Answer 3

gain of electrons and a shift to less positive or negative oxidation numbers

Question 4

Rule 1 - oxidation numbers

Answer 4

the oxidation number of uncombined elements is zero e.g. Na, Al, H2, O2, Cl2

Question 5

Rule 2 - oxidation numbers

Answer 5

in ions made of just one atom, the oxidation number of the elements is the charge on the ion e.g. Na+ = +1

Question 6

Rule 3 - oxidation numbers

Answer 6

the sum of the oxidation numbers in a neutral compound is zero

Question 7

Rule 4 - oxidation numbers

Answer 7

the sum of the oxidation number for an ion is the charge of the ion

Question 8

Rule 5 - oxidation numbers

Answer 8

some elements have fixed oxidation numbers in all their compounds

Question 9

oxidising agent

Answer 9

oxidise other atoms, molecules or ions by taking electrons from them

Question 10

reducing agent

Answer 10

reduces other atoms, molecules or ions by giving them electrons

Question 11

disproportionation reactions

Answer 11

the simultaneous oxidation and reduction of the same chemical species in a redox reaction