OXIDATION NUMBER: the combining ability of an atom
(how many electrons it needs to gain or lose to be stable)
OXIDATION NUMBER: the combining ability of an atom
(how many electrons it needs to gain or lose to be stable)
How to find oxidation number:
How to find oxidation number:
1. Find the number of valence electrons
1. Find the number of valence electrons
2. Decide the easiest way for the atom to get a full outer energy
level. Remember: 8 is great, but for hydrogen, 2 electrons
will do to get stable!
2. Decide the easiest way for the atom to get a full outer energy
level. Remember: 8 is great, but for hydrogen, 2 electrons
will do to get stable!
If an atom has 1, 2 or 3 valence electrons, it is easiest to give
them away.
If an atom has 1, 2 or 3 valence electrons, it is easiest to give
them away.
If it has more than 3 it is easiest for the atom to get some
more to make it stable.
If it has more than 3 it is easiest for the atom to get some
more to make it stable.
3. Write the number of electrons the atom needs to give or get to
become more stable.
3. Write the number of electrons the atom needs to give or get to
become more stable.
4. Add the sign…
4. Add the sign…
+ if the atom gives away electrons
+ if the atom gives away electrons
- if the atom gets electrons
- if the atom gets electrons
OXIDATION NUMBER PRACTICE: Write the oxidation
OXIDATION NUMBER PRACTICE: Write the oxidation
number next to each element.
number next to each element.
Na _____
B_____
Cl _____
Na _____
B_____
Cl _____
K _____
Mg _____
N _____
K _____
Mg _____
N _____
O _____
Br_____
Ca_____
O _____
Br_____
Ca_____
Al_____
P _____
Ne_____
Al_____
P _____
Ne_____