Oxidation, reduction and redox equations

Oxidation

The loss of electrons

Reduction

The gain of electrons

In what reaction do oxidation and reduction always occur together in?

A redox reaction (Involving a transfer of electrons → The number of electrons lost must be equal to the number of electrons gained)

What are the equations that show oxidation and reduction sepeartely called?

Half-equations

Oxidation state of an element

The number of electrons involved when an atom forms a bond

What is the oxidation state of an uncombined element?

0

What is the oxidation state of all group 1 elements?

+1

What is the oxidation state of all group 2 elements?

+2

What is the oxidation state of all group 3 elements?

+3

What is the oxidation state of hydrogen in most compounds?

+1

What is the oxidation state of hydrogen in most metal hydrides?

-1

What is the oxidation state of fluorine in all compounds?

-1

What is the oxidation state of oxygen in most compounds?

-2

What is the oxidation state of oxygen in peroxides (e.g: H₂O₂)?

-1

What is the oxidation state of oxygen in a fluorine compound?

+2

What is the oxidation state of chlorine in most compounds?

-1

What is the oxidation state of chlorine when bonded to oxygen or fluorine?

Positive

Phosphate ion formula

PO₄³⁻

What are the 4 chloro oxo-anions and there charges?

• ClO⁻

• ClO₂⁻

• ClO₃⁻

• ClO₄⁻

Oxidation

An increase in oxidation state

Reduction

A decrease in oxidation state

Oxidising agent

A species that accepts electrons

Reducing agent

A species that donates electrons

How do you balance oxygen atoms in a half equation?

Add water

How do you balance hydrogen atoms in a half equation?

Adding H⁺ ions

How do you balance charges in a half equation?

Adding electrons